Breastfeeding hurt Hurt HURT with my first. It turned out to be misdiagnosed thrush. Thrush can be extremely painful. I built a lot of character with that one. Ugh!
With my next two babies, I assumed that as long as latch was right, and we didn't have thrush--there would only be a few days of "discomfort." Well, I had weeks of actual pain, and I was doing everything "right." I was a trained breastfeeding counselor, had close friends who were IBCLCs, etc. I was like, please check me: pain is supposed to signal something's wrong! Sometimes, IME, breastfeeding hurting may just be something that has to resolve itself--sometimes within days, sometimes weeks...sometimes longer. As far as pain, I'd work to rule out latch, thrush and frenulum (tongue-tie) issues. There's also Raynaud's syndrome that can cause pain, too.
I hope things start feeling better for her asap!