Kingsnake strange behavior? (diarrhea and biting himself)

[mopuim]

I have a male brooks kingsnake who has had a recent change in digestion and behavior, such as pooping a day later after eating and multiple times throughout the week, diarrhea or softer poop (often discolored), and biting his own tail. Some important details are listed below:

-3.5 years old and around 3-4 feet long
-Eats a large mouse every week now in a separate container (always eats well)
-Has an overhead lamp at 50 during the day and an under tank mat
-ZooMed Aspen Bedding in a 40 gallon tank

He used to eat a large mouse every two weeks (and eats well) and never has acted anything like this. He attacks his tail as if he is starving and tries to strangle himself. His tail is all bit up with a bunch of scratches and peeling scales (he usually bites from the side and doesn’t swallow his whole tail). I take him out of his tank when he does this, and he becomes very tight around my hands and turns my fingers purple while trying to tangle himself into the tightest knot. He tightens himself in concerning ways and his body cracks, which I am hoping are just his scales. When he does this, I usually feed him and it resolves the problem until a few days after he poops, where he goes back into hunting mode and tends to be pretty fast and aggressive. He does occasionally bite (which he has only done once when he was very young), and when he does, he makes a slight wheeze sound every few seconds, but he does this when he eats too.

I took him to the vet and it turns out that he had 2 types of bacteria that are common in snakes. Nothing else was wrong with him in particular. They did find some aspen bedding in his system, which I haven’t noticed before. I think he has been getting bedding in his system because he has been attacking himself. They suggested an x-ray to check for impaction, but I haven't seen anything like it since. We got him some oral antibiotics which he took every other day for 2 weeks, and he seemed to get better. He even shed which he hadn’t done in a while. He passed bowel movements at about 4 days after eating, and it had more shape. He also stopped biting himself and acting erratic around his tank.

Since then, I have gotten him new hides that are more secure and a little tree he seems to love climbing on. I put a cover over one side of the tank for more security in case he is stressed. It has been about a month since we went to the vet, and he is starting to have softer poop (or diarrhea) and strange behavior again. He does wait a while (3-4 days) to poop, which seems good, but he is starting to poop multiple times a week and it's more diarrheic. He is also biting himself again in less than a week of eating. I’ve heard stories about people waking up to their kingsnake dead because they started eating themselves, and I really don’t want that to happen.

I tried to make this as short as I could without missing details, so sorry if this is a long read. Any comments or suggestions would be greatly appreciated. Thanks for taking the time to read this!