D.C.
This happens to my about every three weeks. My son isn't biting, but he does cause the sore. I'm not exactly sure how. I think he just doesn't know how to regulate how hard to latch on since he got his teeth. It is excruciating everytime he nurses while it's there. It does eventually heal, in about 4-5 days. I don't stop nursing. I just try to nurse more on the other side, which is hard because the sore side is his favorite side. As long as you don't see any signs of infection, I wouldn't worry too much about it.