Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry to hear that your fellow is walking slowly, seems uncomfortable, is eating poorly, not grooming himself, and has had an episode of urinating where he was laying. Cats are normally very fastidious, so one that isn't grooming himself is a kitty that feels very poorly. It is possible that because he is eating poorly he is too weak to do the things he normally would, but more likely whatever is affecting his appetite is also causing him to be weak, not eat well and not groom himself or care that he urinated on himself.In most cases a lack of appetite is triggered by eating something they should not, too much table food
, too many treats or something they find outdoors.More serious causes include toxin ingestions, viral or bacterial infections, esophageal reflux, a dietary allergy or sensitivity, inflammatory bowel disease, internal organ failure (diabetes
or liver disease), pancreatitis, a full or partial gastrointestinal obstruction, or an abdominal mass.Ideally he would see a veterinarian since he is feeling so poorly and this is unlikely to be simple stomach upset. There are some things we can try at home, but if he's not improving quickly he should see a veterinarian for an examination, some diagnostic testing, intravenous fluids and injectable medication to settle his stomach and get him eating.To try and settle his stomach at home you can give either:1) Pepcid ac (famotidine) at a dose of one quarter of a 10mg tablet per 5 to 10 pounds of body weight every 12 hoursOR2) Prilosec (omeprazole) at a dose of one quarter of a 10mg tablet per 5 to 10 pounds of body weight every 24 hoursThese are acid reducers and may help settle his stomach and get him feeling better and hopefully get his appetite back. They are quite safe and can be used for several days if necessary.I would pick up all food for now and water for a couple hours to allow his stomach to settle after the acid reducers.In a couple hours when you give him water make sure it is in small amounts only. To get some electrolytes in you can offer him a 50:50 mix of pedialyte and water or some low salt chicken broth.In 3 to 4 hours offer a bland diet of 2/3 boiled, minced, white, skinless chicken and 1/3 boiled, white rice mixed with some low salt chicken broth to make it easy to lap up and swallow. If he refuses that you can offer a little meat baby food. If he refuses both then don't push it, he needs veterinary care.If things go well and he does eat well and doesn't vomit feed him the bland diet for 2 to 3 days then slowly start to mix back in his regular food, a little more at each meal. It should take about 5 to 7 days to slowly convert him back to his regular diet.If he continues to not eat even with the acid reducers, runs a fever (more than 103F rectally), or has a lower than normal temperature (less then 99F), or has a tense painful belly he should see a veterinarian for an examination, diagnostics, injectable anti-nausea drugs intravenous fluids and supportive care.Please let me know if you have any further questions.