This is a simple one;
You have been overfeeding your ball python so much that he finally decided that since you weren't going to stop feeding him, he should take matters into his own hands (so to speak) before you kill him with food.

I see this all the time; someone has a baby ball python who WILL eat anything so the owner (usually a dude, this matters) figures that since the animal is willing he'll just keep feeding him so he can have the biggest yearling ever seen.
Big mistake.
More than likely, not only are this animals kidneys in really rough shape, you've most definitely shortened his lifespan considerably and forced him to go off food because you couldn't regulate his eating.
Please don't come back and say you don't powerfeed, because any animal that triples in weight in three months has been powerfed.