Agree ^ ^ ^. Does he have both warm & cool side hides? Most BPs won't accept food if they're out in the open- wait to feed until he's looking out of his hide, at night. And until then, don't offer too frequently, that just adds stress (for both of you, lol).
Double-check his temps. anyway though...how are you taking his temps.? Don't rely just on what a thermostat says, double check where the snake is- and do so with an accurate method. How are you taking his temps? When it's winter & your room/home gets cooler, their enclosure can lose more heat than you might think- & what worked in fall & summer, might not be okay now.