Your husbandry sounds good. I still think it's stress.

There are ball pythons out there who require more work than others. But something tells me this is not the case.

I'm trying to think. Has anything around his cage changed since this happened ? Different lighting, or new furniture or anything like that ? I know birds are extremely sensitive to changes in environment, perhaps he is as well.

As a kind of "shock" therapy for his stress, try filling up most of his tub with balls of crumpled paper. This is a common trick for hatchlings. Give him a few weeks in the tub with paper, and don't feed him in that time. He won't starve. If he stops the striking behavior, gradually remove a few of the paper balls at a time until you succeed in removing them all.

Take a really good look at your ball when he's a rest and see if you notice you can see skin between his scales, if you can it's a good bet he's overweight, and you should cut back on his food. If you can't, he's not overweight yet. If you are truly concerned about him eating too much you can easily cut back. He may not like it, but he certainly won't starve.

As far as handling goes, if you cannot get him to stop the striking behavior, it's still important you handle him. I don't know if you've ever been bitten, but it's really not a big deal. Especially if it's a defensive strike, since he'll hit and let go at once. If getting him out is an issue, approach him with your hand held palm out, to give him less of a target to latch onto. If he's really difficult, you may want to consider a small snake hook just for getting him out, Once you have him out, keep him in contact with you. If he's really flighty, you'll have your work cut out for you, but don't let him strike you and then get away. He'll associate biting with freedom, and that's not going to help you at all.

Don't give up on him yet, I'm confident with a little patience and work he'll come around.

Gale