What causes a ball python to from being calm and barely moving to being very active and when you hold him hover his head like he is ready to strike this has all taken place in about a week.?

if his tank is to small he we be feeling claustrophobic and threatened by any body who goes to touch him. or he is hungry, but there could be some other cause so i recommend you get him to a vet as soon as possible. hope i helped. but was he due to be fed when he started acting all weird? if so he will be hungry. but if you feed him and he sees your hand while you feed him he will associate your hand with food so that could be why he goes to strike. this is not a fake answer it has happened to a friend, he could be sizing you up to eat you so don't leave him unattended out of his cage if he has one but if all this continues even after you've fed him i would recommend getting him to a vet because they can tell you what to do in this situation.