Friend, vomiting can be caused by many different conditions. It will be difficult for me to determine the exact underlying cause without a hands on examination and some testing. But, common causes are: Dietary indiscretion, pancreatitis, ingestion of a foreign body, infections, etc. to name a few causes. Him shivering could be a sign of discomfort which can be caused by any of the above conditions. Or, he could have a fever. If you are able to pick up a digital thermometer and take his rectal temperature that would be great; the normal temperature in a dog is between 99.5-102.5 F. I would also recommend a hands on examination with family vet to run some testing like xrays and blood work to determine the exact underlying cause of his symptoms. In the meantime, in any case of vomiting the first thing to do is give the stomach time to rest. This is what you can do:
1- Do not give things like Pepto Bismol or imodium. Start him on Pepcid AC (famotidine) 10mg tablet every 12 hours for the next 2-3 days. You can buy Pepcid AC over the counter in any pharmacy.
2- No food or water for 8-12 hours. Need to give his gastrointestinal tract time to rest. Keep him indoors in a cool room when fasting.
3- After 8-12 hours offer a small amount of water. Wait half hour, if no vomiting, offer small amount of rice (50%) and boiled boneless chicken or ground beef (50%) 4-6 times a day. Keep on this diet for several days then wean into regular diet.
4- Follow up with your family veterinarian for a hands on examination.
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