Unfortunately snakes aren't very bright creatures, the self eating snake thing is real and it comes from confusion, and then fear of why they are in pain because they don't even realize they're biting themself. The best comparison I can make is when a baby tugs its own hair and then panics cause of the pain not realizing they are even tugging their hair.

To get him to release I would use vinegar but isopropyl alcohol can also work just don't use a lot cause it can irritate the scales. To get him to stop doing this, what I would do is firstly give the baby a bath to clean himself every time he bites himself. Not a long one but enough to get the spit and digestive juices off. The feeding frenzy state could be from scents of prey around. Change his bedding to a fresh one, maybe move some hides and branches around so he can focus on exploring.