Poor kitty. I too think you should take your cat to the vet, or at least give him a call. It's important that your cat drinks, so put bowls of water around in different places. Cats often like running water, so try that also.

There are diet foods for almost anything these days, so I think you should get a bag of that - preferably from a vet! The stuff they sell in pet stores are not as good, and the vet will know which one is the best for your cat.

Good luck!