Is he WC? If so, he's probably not eating because it is winter. Just stick with him until the weather warms up and he may begin eating again. Also try scenting food items with lizards or frogs. Have you tried feeding him at different times of day? I have had a coachwhip that would only eat in the middle of the day and other kinds of snakes that would only eat at night. Make sure his cage is warm enough, also (85+ on one end). Keep trying and good luck.