Sore nipples.

My son is 3 days old and nurses often. Even using a shield half the time, my nipples are cracked, bloody and so sore it almost makes me cry when he latches on. I don't remember being in this much pain with the last 3 kids. And I don't remember how long it takes until I'm used to it. The only time it's barable is about an hour after I take my c-section meds. Has anyone else experienced thisr evenly enough that you know how long it was until it stopped burning??