leave the snake alone for the next week. Then go to the pet store and ask for some gerbil poop. Its a weird question to ask but people have used this method with great success. Normally i would say try a baby gerbil but they are hard to come by. Rub the gerbil poop onto the hopper or what ever your trying to fed the snake and let it sit for a few hrs in with the snake in total darkness. This may do the trick. The snake is prob stressed or your temps arnt up to par.