Please help, blister on nipple😭

So my son is 11 months, EBF on the boob, won’t take a bottle. A few nights ago I noticed my nipple really hurt while I was feeding him. I look and see a small blister type thing on the bottom of my nipple. (So I assume) I’ve been feeding him like regular since, but today has been soooo bad. The pain while feeding him is unbearable. I really don’t want to feed him on that side and I’m currently extremely lopsided🥴 I used my Hakka to relive some pressure but it didn’t do much. No idea how it happened or how to heal it