Why so painful??

Been breastfeeding for almost 9 months now with absolutely no pain or problems. Now all of a sudden one of my boobs is VERY painful. He eats the same amount as always and I’m not engorged at all. It is very tender to the touch and when he latches on!!!! holy cow it hurts so bad. I’ve been just pushing through the pain but I’m wondering if anyone else had this happen and if they went to the doctor for it. I don’t want to have to go to the doc right now unless it’s completely unavoidable. Any advice?