Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry to hear that Blossom is vomiting yellow material and clear mucous. often with food.
Yellow in the vomit means that the small intestine is refluxing bile into the stomach so that when she vomits you see the yellow color. That isn't normal as bile doesn't belong in the stomach, and it does mean that there is some reverse motility, but it isn't specific for any particular disease process.
If she seems to feel well otherwise some dogs seem to vomit more on an empty stomach so feeding her small meals several times a day, and maybe a snack before bedtime, may be very helpful. It may also be helpful to put her on an acid reducing medication as too much stomach acid, especially on an empty stomach, is very irritating and predisposes to vomiting.
In many cases vomiting is triggered by eating something they should not, too much table food, too many treats or something they find outdoors.
More serious causes of vomiting include viral or bacterial infections, chronic pancreatitis, esophageal reflux, a dietary allergy or sensitivity, inflammatory bowel disease, internal organ failure (kidney or liver disease), a full or partial gastrointestinal obstruction or even infiltrative cancers such as lymphoma.
If she seems to feel well other wise you can give acid reducers to try and settle her stomach. If she seems to vomit most in the morning after having an empty stomach overnight I recommend giving her a dose before bed so that it is in her system in the morning. You can give either:
1) Pepcid ac (famotidine) at a dose of ¼ of a 10mg tablet per 5 to 10 pounds of body weight every 12 hours. I understand that you have used Pepcid, but I wanted to make sure you were using an appropriate dose.
2) Prilosec (omeprazole) at a dose of ¼ of a 10mg tablet per 5 to 10 pounds of body weight every 24 hours
These are both acid reducers and should help her feel better. They are quite safe and can be used long term if necessary. If you have been using Pepcid at an appropriate dose and she still vomits then it is worth trying Prilosec. Some dogs do better on one rather than the other.
I would pick up all food for now and water for a couple hours to allow her stomach to settle after the acid reducers.
When you give her water make sure it is in small amounts only. If she drinks too much too quickly that can lead to vomiting.
In case this is diet related try offering a bland diet of 1/3 boiled, minced, white skinless chicken or boiled, lean hamburger, all fat drained off the meat, and 2/3 boiled, plain, white rice mixed with some low salt chicken or beef broth to make it easy to lap up and swallow.
But if things go well and she does eat and doesn't vomit feed her the bland diet for 2 to 3 days then slowly start to mix back in a sensitive stomach food, a little more at each meal. It should take about 5 to 7 days to slowly convert her back to her new regular diet. Both Hills and Royal Canin make a sensitive food diet available at the pet store.
If she continues to vomit even with the acid reducers and bland diet, runs a fever (more than 103F rectally), has a tense painful belly or if she refuses to eat she should see a veterinarian for an examination, diagnostics, injectable anti-nausea drugs intravenous fluids and supportive care.
Please let me know if you have other details or a particular question based upon my response.