You may well have reason to be concerned. How long ago was the "other day?" If it is 2 or more days, call the vet again. Given the vomiting and the tarry substance and not eating you should think about getting her seen by a vet today.
What was the mess that she threw up along with the plastic? Food she had been fed or other non-food related material? Does she chew and eat toys or other objects regularly?
Could she be throwing up somewhere that you don't see? When did she last defecate? Does she have a normal stool or diarrhea?
Was the plastic part of a bottle that contained drugs or something else you can identify?
Would the tar like substance be something that was in a plastic bottle? Could she have eaten oil or grease? Another possibility is that she has some gastric or intestinal bleeding. Partially digested blood looks black and tarry. Often this is seen in stools, but can be in vomit if the vomit includes intestinal and not just stomach contents.
Vomiting can be a sign of intestinal blockage, irritation or toxic substances. No defecation can be a sign of blockage. Diarrhea is a sign of general intestinal upset and some drugs or poisons. Sleeping a lot is a sign of feeling poorly and/or fever.These are signs that indicate a need for veterinary care and some could be serious.
Plastic by itself is not likely to cause a rash. The rash could be related to the "mess" depending on what that contained. It could also be unrelated caused by contact allergy, grass or thorny plants. The continued biting at herself indicates that she is itching. If the benadryl didn't stop it, she needs an accurate diagnosis and a more effective treatment.
The questions I asked are intended to get you to think about what might cause the problem you describe. Let me know if you can provide more information based on the questions or if you have other follow up questions.
Ok, I will try to answer your questions. It is a Saturday in a small town, and I am not sure I can get her in anywhere, besides the fact that I am recovering from the flu and not that well yet. Rough week here.
I cannot accurately describe the "mess". I was very ill, and I tried to clean it up as quickly as possible. The one thing that was very noticable though, was a good size piece of plastic or rubber. I could not identify it, and have seen no evidence of it belonging to anything. She threw up again not long after that, but it was clear and free of anything really. My dog leads a very sheltered life. She lives inside, and only goes outside to a relatively small fenced in area. We have been watching her closely when she does go out. She has been defecating, but it seems in small amounts, and not to her complete satisfaction. It may border on diarrhea...I'm not sure. She threw up outside yesterday morning. My husband noticed it and said it was kind of green. She spends most of her day sleeping. She only seems to get up for the most part to go outside, and then back to resting. When I gently press around on her belly and back, she doesn't seem to have any complaints. Other than sleeping a lot, she does not seem to be in any discomfort. Today when we woke up, we found the dark substance that I referred to. When I tried to clean it from our next to white carpet, it had a strong yellow color to it. Today for the first time, she seems interested in what we are eating, but not her food or water. How do you know if she has fever? Anything, I can give her to make her feel better? Thanks so much
The green color to vomit is caused by bile. It indicates that the some of the vomit is from her intestines, not just her stomach. This is common and a normal aspect of vomiting. The dark substance today also sounds like bile, which reduces my concern about blood and bleeding. it is also good that she doesn't seem to have any pain when you press on her abdomen. The sheltered life eliminates a lot of the worry about eating other junk, particularly toxic substances.
I know we all want to give our critterkids something to make them feel better. However, giving nothing is sometimes the best thing we can give. Hold off on offering her food and water for a while longer. Whatever has her upset needs to work its way the rest of the way out of her system. Her interest in your food indicates that things are improving.
My normal protocol for uncomplicated vomited follows.
Withhold all food and water for at least 6 hours after the last time she vomits. She should be pretty close to 6 hours now. After 6 hours, offer her a tablespoon (15 cc) of water or an ice cube if she likes those. Repeat every 15 minutes if she doesn't vomit. If she vomits, withhold everything again. I'm hoping she handles the water OK because she has gone a while without water already.
After getting a tablespoon of water every 15 minutes for an hour, increase the amount to 2 tablespoons (1 oz) every 15 minutes for another hour. Again, if she vomits during this time, withhold everything again.
After 2 hours, she can have a few laps of water or 30 cc (2 ozs) every 15 minutes for another hour. The idea is to work her up slowly to where you can leave the water out and she will not gulp it. If she starts gulping, she is likely to start vomiting again.
Start introducing food 6-12 hours after she is drinking without vomiting. Don't rush it. Her stomach needs to be empty for a while to get over the vomiting reflex.
When you start to offer her food, give her a small amount (1 tablespoon or 6 bits of kibble or a small piece of biscuit) of her normal dog food. Repeat every 15 minutes for an hour and don't feed her for another 2-3 hours.
After a couple hours, she can have about 1/8 of a normal meal.
At the next normal feeding time, she can have half the normal meal and then return to a normal feeding schedule.
The exact timing is not important, but the idea of withholding everything, reintroducing water and then food over about a 24 hour period is the key.
If she continues to vomit without any food or water particularly if she vomits large volumes or gets watery diarrhea, she should see a vet so she can be given fluids, meds as needed and a diagnosis.
The following gives the method for checking temperature and the circulatory system to provide information on her overall status.
You can take the temperature using a human thermometer. Lubricate the end and put it in the rectum 1-2 inches using gentle pressure. Remove it after a minute. Normal temperature for cats and dogs is 101 - 102.5. 103 is a low grade fever and 104-106 is the common range for fevers.
Look at the gums. They should be pink, not white, blue or bright red. Press on the gums behind an upper canine tooth using your finger. It will blanch white with the pressure and be white when you first remove your finger. It should return to pink in 2 seconds or less. If it takes more than 3 seconds, it indicates poor circulation, which can be caused by dehydration or heart problems.
A fever, pale gums and/or slow capillary refill time are indications of a more serious problem than simple vomiting caused by dietary indiscretion.
It does sound like a rough week and I hope both of you feel better very soon!
I'll be around for a while and on and off the computer today and tomorrow for any further questions or support.