Why is breastfeeding suddenly SO painful? 9 months PP.

Up until this point my son and I have had a pretty easy breastfeeding journey but the last few days have been SO painful. My nipples are so so so sore every time I nurse and they’re super sensitive and hot when not nursing.

He did just get his first two teeth but he’s been pretty good at not biting. Could it be the friction from his teeth anyway?

Haven’t had my period back yet so I can’t be pregnant.

Don’t think it’s thrush because they aren’t itchy, not flaky, and don’t really sting or burn they just HURT.

Any ideas?