Most animals become mean when hurt. And ta-da, your snake's burnt. I say get him to a vet, and get him some Baytril IMMEDIATLY. I've lost a snake to burns, because I thought I could treat her. I was wrong, and by the time I got her on meds, it was too late.
Also, the reasons he might not be eating:
1- Internal parasites. Get him some Panacur.
2- When are you feeding him? BPs are nocturnal.
3- Try leaving him alone with the (dead!) food over night. Sometimes they're too anxious to feed with you around. So leave them in a box, in the dark with no disturbances, overnight.
As for the aggression-
1- Wear gloves. If he bites, it'll only hurt the gloves. Plus, he's getting used to being handled.
2- Put one of your stinky (smells a lot like you - wear it for a couple of days) shirts in the cage with him. If he gets used to your smell while he knows it's safe, he'll be less likely to bite.
3- After you get the burn taken care of, if he's still aggressive, try leaving him completely alone for about a month. I had to do that with one of my aggressive ones. Eventually settled down on her own, once she knew there was no danger.
Here's my big tip of the day - go to a vet who knows what they're doing. Just start calling vets in the phone book, and ask who treats snakes. When you find someone, remember "Baytril" (an antibiotic, most common treatment for burns and resp. infections) and "Panacur" (good for the more common parasites). If they prescribe anything else, ask WHY. If they can explain to you why, in detail, then they're good snake drs. Also, you should get a cream for the burn. I can't remember the name of it off-hand, but yeah.
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-Irish
My Snakes