The winter is whats doing it most likely.
So long as he still looks fine, I wouldn't worry. Periods of inactivty are not all that uncommon. Continue to offer him food at his scheduled times.
One of my boys hasnt eatten for nearly 2 months, but hes still a healthy weight and isnt losing that weight quickly, so I'm not concerned at all.
An overly active ball python is actually more concerning then an inactive one. Overactivity can be a sign of stress.
In short, don't worry, your little guy should be fine![]()