it could be because of the winter, sometimes ball pythons are known to go off feed for the winter. I feel this is because the cool temps turns on the breeding season, and my ball pythons do not like to eat during this time. Also ball pythons are know for vasting in general, I believe the longest recorded without feeding was 28 months, I wouldnt worry to much unless, he is to the point where his weight is an issue, and then force feeding comes into play. I had to force feed one of my rescues a hatchling normal male, for 3-4 months before he would eat on his own. Goodluck, and keep us updated