Vomiting and diarrhea can be caused by many different medical conditions. It will be difficult for me to pinpoint the exact underlying cause without a hands-on examination and some testing. But, common causes are dietary indiscretion, ingestion of a foreign body, infections, or even part of a systemic disease, etc. to name a few causes. The fact that he has had diarrhea and vomiting for 2 days I am concern about his hydration. I would definitely have him checked by an ER veterinarian; they can start him on IV fluids while they run some testing to determine the exact underlying cause. I realize that this answer may not be entirely to your liking, and I regret being the bearer of information that you really don’t want to hear. But it would be unfair to you and unprofessional of me were I to provide you with anything less than truthful and honest information. I hope you understand. Until he is seen by a veterinarian this is what you can do:
1- Do not give things like Pepto Bismol or Imodium. Start him on Pepcid AC (famotidine) 10mg 1/4 tablet every 12 hours. You can buy Pepcid AC over the counter in any pharmacy.
2- No food or water for 3-4 hours. Need to give his gastrointestinal tract time to rest.
3- After 3-4 hours offer a small amount of water. Wait half hour, if no vomiting, he can continue to have water but leave him without food for 8-12 hours. Then, offer a small amount of rice (50%) and boiled boneless chicken or ground beef (50%) 4-6 times a day.
4- Follow up with a veterinarian for a hands on examination as soon as you can.
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