my cat's back legs

so last night I noticed my one year old male cat is having trouble walking, he can barley move back his legs. and when he does get up to walk his legs become very wobbly and he has trouble sitting up. and we cant seem to get him to eat anything. can anyone tell me what it might be? 

Hi and welcome to The Cat Site. I am sorry your first post has to be here with a problem. A good rule of thumb with cat's is when things change from normal a vet visit is in order. This is especially true for your cat because the problem involves his appetite. Cat's can develop some serious situations with the liver when they don't eat. Please don't wait too long to have your cat seen by the vet. The problem with the cat's legs and the appetite issue may or may not be connected. But you need to know. I hope it is nothing too serious. Anyone here can only make a guess.

Yes please take your cat to the vet.  These symptoms are troubling.

He is very young to have trouble walking.