Hello, welcome to JustAnswer! I am a Veterinarian and will help you right away!
Hopefully it is just a really bad upset stomach
(gastroenteritis). We see it all the time.
Here are two possible solutions you may have at home for also helping to settle the stomach:
----> Pepcid AC : It comes in 10mg, 20mg, and 40 mg tablets. It can be given at 1mg per 2 pounds of dog, so a 20# XXXXX would get one 10 mg tablet.
You can repeat this every 12 hours.
----> Peptobismol: DOGS ONLY! Generally, the advised dosage is 0.5-1ml of Pepto Bismol per pound of weight, roughly a 1/2 to 1 whole teaspoon per 5 pounds. It should be administered every 6-8 hours. If you're using the tablets, that is equal to ¼ tablet per 20 pounds of weight every 6-8 hours.
Please note that Pepto should not be used for nursing or pregnant pets, and it isn't for pets that have history of bleeding
A bland diet of chicken and rice is good idea as well since it is easy to digest and gives the digestive tract a break. Often you can tempt them with this when they won't eat anything else. 1/2 cup of rice to 1/2 cup of chicken is a good blend. Boiled chicken, with no skin.
BUT IF YOUR PET WON'T eat that, you could try lean ground beef instead, or cottage cheese. Most dogs will eat that.
For sure if the vomiting doesn't resolve over the next two days, I would recommend:
Fecal test to be sure there are no internal parasites
A full physical exam by your Veterinarian
And maybe even x-rays to evaluate the abdominal organs/ or ultrasound.
Hopefully, your pet is better soon!