I am sorry to hear you are worried about Moki. My name is Rebecca. I am a veterinarian and will do my best to help.
Anytime a cat does not eat for more than a day, I am very concerned. Cats tend to be secretive about not feeling good, and not eating is one way they tell us something is wrong. Another concern when a cat does not eat is dehydration, and he is he now dehydrated that complicates his illness. Is he willing to take any liquids such as water, or broth?
If you look at his gums, are they a normal pink color or do they seem pale?
Cats vomit for dozens of reasons: infections, an intestinal blockage, inflammatory bowel disease, pancreatitis, liver or kidney disease, even heart disease or heartworm infections cause cats to vomit. If he were my own cat, or my patient, I would begin with a thorough physical examination: palpate internal organs and lymph nodes, feel for an intestinal obstruction, take his temperature with a thermometer, check his hydration, listen with a stethoscope, feel his pulses, etc. You can check him for dehydration by gently pinching skin over his shoulders and letting go. The skin should be back in position in less than 1 second; if it stays pinched longer than that he is dehydrated, and in need of supplemental fluids.
Diarrhea can also indicate infection, parasites, liver disease, inflammatory bowel disease, pancreatitis. Losing fluid in diarrhea will also contribute to dehydration.
He should be examined and treated by a veterinarian as soon as possible, especially if he is dehydrated. Try to get him to take water, broth, tuna juice. You can try giving him 1/4th of a 10 mg Pepcid AC (famotidine) for vomiting, but an injection for vomiting can be more effective.
I am very worried about a cat that has not eaten for a couple of days. To know the best treatment, you have to find out where the problem is, and we begin with a physical exam.
Let me know how he is doing and what other questions you have. Rebecca