I have not heard back about his stool color, but will leave my thoughts about what you have told me. Now I share your concern about your lad and have to warn you if he is that nauseous that he cannot keep even water down and vomits when you put pressure on the stomach; this is a situation where we’d likely need his local vet to bypass his mouth with injectable anti-vomiting medication to give us a chance to address this for him.
Just to note, as long as those stools aren’t black (which is a sign of gut bleeding), then we’d be suspicious that his signs are not related to a stomach ulcer or damage and instead could be due to bacterial or viral gastroenteritis, pancreatitis, parasites/protozoa infections, general dietary indiscretions, and ingestion of harmful items (ie toxins, plants, non-edible items). And that last one is a real concern if he is a known foreign body eating dog.
With this all in mind, since he has just vomited, the first step at home will be to rest his stomach for a few hours. Food should be withheld and water offered in sips or as ice cubes. If he settles a bit, you can try an OTC antacid like Pepcid (More Info/Dose @http://www.petplace.com/article/drug-library/library/over-the-counter/famotidine-pepcid), Zantac (More Info/Dose @ http://www.petplace.com/article/drug-library/library/over-the-counter/ranitidine-hcl-zantac), or Tagamet (More Info/Dose Here @ http://www.petplace.com/article/drug-library/library/over-the-counter/cimetidine-hcl-tagamet). Whichever you choose, we’d give this 20 minutes before offering food to allow absorption. Of course, do double check with your vet if he has a known health issues or is on any medications you haven't mentioned. Though again if you give this and he cannot keep it down due to nausea that is usually a red flag that we need him seen now.
Though if we can get him settled, then you can try small meals of a light/easily digestible diet. Examples you can use are cooked white rice with boiled chicken, boiled white fish, cottage cheese, or scrambled eggs (made with water and not milk). The aim of these diets is that they will be better tolerated/absorbed by the compromised gut. Therefore, it should get more nutrients in and result in less GI upset and less diarrhea. You can also add fiber to this (ie canned pumpkin, all bran) to bulk up his stools. As long as improvement is being seen, I usually advise continuing this until the signs are settled, and then weaning slowly back to what you normally feed.
Since dehydration is a risk with both his upper and lower gut signs, we need to keep an eye on his hydration. To check this and make sure dehydration isn’t an issue, there are a few parameters you can test. Further to checking for gum moisture, you will want to make sure his eyes are not looking sunken and that he doesn’t have a "skin tent" when you lift the skin. To see how to check these, you can find a good video HERE (http://www.ehow.com/video_12232503_dog-dehydrated.html). If you do see any of these signs already, then that would be our cue to have him seen before this becomes an additional issue (especially since its often dehydration that makes them feel unwell).
Finally, as long as there is no blood in his stills nor black feces, you can consider trying a pet safe anti-diarrheal. As I am sure you appreciate, these would not be a cure for infectious issues; but it can still be of benefit. It will reduce diarrhea load, allow the body to absorb more water/nutrients, and soothe the upset gut. In regards ***** ***** options, the one we most commonly use is OTC Kaolin/Kaopectate (More Info/Dose @ http://www.petplace.com/article/drug-library/library/over-the-counter/kaolin-and-pectin-kapectolin-k-p)). Otherwise, Propectalin, Canikur, Fast Balance, and Protexin Pro-Fiber (which is available OTC at vets, pet stores, and even Amazon) would be another option. All will slow diarrhea and those last ones have the added bonus of providing support to the delicate good GI bacteria. So, these can be used as a short-term means of soothing his upset GI.
Overall, a wide range of agents could trigger the GI upset we are seeing. If the stools are black, then we’d want him seen right away for concern of a bleeding ulcer or trauma to the gut from something he ate. Otherwise, you can try the above to see if you can settle his stomach. Though if he cannot keep that or water down, appears dehydrated already, or doesn’t respond to the above within 12-24 hours; then we'd want to get his vet involved. They can assess his hydration, rule out fever, ensure nothing in his stomach that shouldn't be, or any sinister viruses present. Depending on their findings, his vet can treat with injectable anti-vomiting medication, gastroprotectants, fluids, +/- antibiotics to settle his stomach and get him back feeling like himself.
Please take care,
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