feeding my corn snake

Question
hi my 1-1/2 yr old corn snake has not eaten in 4weeks after the first week he shed but hes still not eating when ever i put a rat pup near him he smells it the backs off like hes too scared of it im not sure what to do??

Answer
So, just to confirm, this is a snake that WAS eating but has stopped???  If so, he COULD be in breeding mode (some of mine are right now), or he could be sick.  Have you tried anything besides rat pups?  Try a mouse for instance.  Sometimes they just get "screwy" and you have to change things up.  Check him for any trouble breathing, mucus/slime/bubbles around the mouth, audible breath sounds, etc.  And you notice any of that it's vet time.