This happened to me and I don't have much of a good news story to tell I'm afraid. I was treated for thrush for weeks and it didn't help at all. My obstetrician was finally the one who diagnosed vasospasm and gave me a medication that's usually used for high blood pressure (sorry, I can remember what it was called). It made little to no difference and 17 months later feeding DS is still painful, though nowhere near as bad as it was at the start. I still wince every time he latches. I've persevered through sheer bloody mindedness and I think the only thing that has improved it a bit is that his mouth is bigger now. I can't go bra-less as I cant stand my top rubbing my nipples, or even bed sheets. It's not much fun!