My DD does this all the time, I have found that a bit of bonjela before a feed helps and also making sure she is hungry so she focused on filling her tummy (although this won't help when he is comfort sucking). Good luck.
There a couple of tactics you can try. If the baby is biting and won't let go you can try pushing his head into the breast so he has to let go to be able to breathe.
Or start teaching some manners at the breast. If you are a smart baby you don't bite the breast that feeds you. Unlatch immediately that he bites and firmly say "No biting, it hurts me". Everytime he bites you do this. He'll soon learn not to interupt his feed by biting.
Teeth aren't involved with sucking so if he's activiely feeding he won't be biting, it'll only happen if he's messing around with the breast, playing with his food, which is fine so long as he doesn't hurt you whilst he at it.