My gut feeling is to say that just a light swelling from bumping into the enclosure walls probably doesn't need to be medicated, just kept clean. A picture of the injured area is always helpful.
I've known some people who will use diluted betadine for mouth injuries (drawing on my experience w/garter snakes here) but I prefer to use diluted hibiclens, which you can buy at your local pharmacy. Just diluted about 1 part Hibiclens/4 parts water.
As I said, this is drawing on my experience with garters, so you may want to wait till someone with more BP-specific knowledge chimes in, though I can't think of a reason that this wouldn't also apply to BPs.
A phone consultation with a vet never hurts anything especially when the mouth is involved, but I've seen betadine very commonly recommended by a lot of different sources for many different herps as a general disinfectant w/o a prescription... I've never actually heard of anyone getting a prescription for it. Is this something specific to the BP community that I'm unaware of?