I have a 10 year old long haired tabby. He is neutered. I feed him Science diet original dry food normally but had to get a different dry flavor last time. He has been vomiting up the food along with hairballs. I also noted this evening his hind end reeks of urine/ammonia. I tried washing off with wet wipes to help clean it and encourage him to lick more. Cleaned a clump of dried feces out of the hair. I changed the litter box. I did research on cat urine smell..suggestions include vet for UTI or kidney disease. Do you feel that really the issue is the food change? Litter box issue? Any suggestions?