Are you sure the snake is not dehydrated at all? A method I have used with bad feeders is to put them in a small rub full of water as a rehydration therapy for a couple of hours, then place them in a smaller enclosure in a really quiet and dark area and cover them so not as to disturb them al all for a couple of weeks. Then try feeding again. It's worked for me many times. Best of luck whatever you try.