Take him to another Vet asap! The same thing happened to me with my cat and it turns out he had eaten something that was blocking up his intestines. He had surgery and is doing fine now! My original vet said nothing was wrong...boy was HE WRONG!!! Good luck. I hope it all turns out okay! Poor kitty!!!

 Absolutely, get another opinion! I'm surprised your cat isn't severely dehydrated by now. I had a cat also that this happened to and he also had eaten foreign objects that blocked his intestines. Some cats are attracted to strange things. Mine like anything stringy (yarn, floss, ribbon and HAIR BANDS and rubber bands). Mine also needed surgery and everything turned out okay, but don't let this go! Good luck!

 Go to another vet. If he or she is not eating and drinking and has been vomiting the cat is probably now dehydrated. The cat might have gotten into something. A second opinion may save your cats life if it not already too late. I wish you the best of luck.