I couldn't quite tell from your second post - when you say "we" are "skipping" meals, is he refusing to eat or are you not offering the meals because of the vomiting?
If you are indeed not offering him meals because he vomited, that may be part of the problem. When cats get very hungry, they sometimes eat too fast and make themselves sick, so it may be turning into a cycle where he eats too much, vomits, gets really hungry, then eats too much again etc.
If you're offering him all his regular meals and he's just refusing to eat, I agree that it could be just about anything. Then your best bet would be to take him to the vet.
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