First, we do need to tread with care whenever there is any doubt that a male cat can pass urine. This is because urinary blockage in male cats is an absolute emergency situation and can appear as you have reported. And I am quite concerned about Milo specifically if he reacted and vocalized when you pressed on his belly. As well, while we can see vomiting/diarrhea together with gut based issues, the fact he has just passed a bit and has mucus just makes me concerned that these could have been side effects of straining to pass urine. So, if you think he may not be able to pass urine, then we'd want him see right away by the local ER vet in case of a life threatening urinary blockage. To find your local ER, you can check @ http://www.vetlocator.com/ or via http://www.veccs.org/index.php?option=com_hospitals&nationid=1&Itemid=193
Otherwise, if you are sure he can pass urine then we can focus on the more common GI centered differentials for his signs. In regards ***** *****’d be most wary of a gut infection, pancreatitis, parasites/protozoa infections, general dietary indiscretions, and ingestion of harmful items (ie toxins, plants, non-edible items).
With this all in mind, as long as he can keep water down, we can try some home supportive care to try to settle his stomach. To start, if he hasn’t just vomited (since otherwise we’d need to rest the stomach for a few hours first), you can consider treating with an OTC pet safe antacid like Pepcid (More Info/Dose @http://www.petplace.com/article/drug-library/library/over-the-counter/famotidine-pepcid) 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. Also if you give this and he cannot keep it down due to nausea that is usually a red flag that we need to bypass his mouth with injectable anti-vomiting medication from his vet.
Once he is more settled, you can plan to try small meals of a light/easily digestible diet. Examples you can use are boiled chicken, boiled white fish, or scrambled eggs, or meat baby food (garlic/onion free only). 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 will help with the loose stool 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.
Overall, a wide range of agents could trigger the signs we are seeing. If there is any doubt he cannot urinate or if that belly is quite uncomfortable, then we'd want him seen now. Otherwise, you can consider supportive care to try to 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 +/- antibiotics to settle his stomach and get him back feeling like himself.
Please take care,
If you have any other questions, please ask me – I’ll be happy to respond. **Afterwards, I would be grateful if you would rate my service by clicking on the "Rate my Expert' button at the top of the page as this is the only way I am credited for helping you. Thank you for your feedback!: )