Help please!

I was making out with my boyfriend and he started pinching my boobs and after a couple of minutes he stopped but when he stopped i got a massive burning sensation in my left nipple. It burned for a good 5 minutes until stopping and when i went in the shower it started burning again. Does anyone know why? Also when i woke up this morning it was redder compared to the other and now has little marks on the edges of my nipples that look like a scratch. Help?