Biting while breast feeding
This advice seems counter intuitive, but I was told to do this by my lactation consultant and it has worked very quickly for all 3 of my kids. When your baby bites while feeding, push their head into you breast/body firmly until they release and break their latch. Mine all quickly learned that biting meant they would have to break their latch and stop eating and they all stopped. You could also try to break their latch yourself, but I found pushing them into my body was much quicker and involved less pain since I didn't have to struggle to pull my nipple out of their mouths.