Around the time of my period, I used to get a sharp pain in one spot on my right breast. I had this almost every month for a couple years, but there was no lump that I could feel. One night, I felt a lump there, and it was painful. I went to two doctors who had a lot of trouble actually finding it at first because it's so small, but I ended up going to a breast specialist, and she did an ultrasound of it (more effective than a mammogram because of the size of my breasts and because of where the lump is located... I did have a mammo, though, at first, I don't even know if the lump showed up on the mammo). Anyway, she ultrasounded it and did a needle biopsy, and everything was fine. I just went back a few times for follow-ups to make sure the lump wasn't getting any bigger. It was a fibrous mass, I guess, and nothing to worry about. It changes size a little with my monthly cycle, which is why it hurts at that time of month, but over a year and a half that the doctor monitored it, it stayed the same size.
I'm sure your friend will be fine. The best bet is for her to see a breast specialist if there is one in her area, or at least get a mammogram and/or ultrasound done to see if there's anything there.