Just noticed it after her shower, she says its not really itchy, a little sore in that area??
Kym, sounds like she might have an infection or skin issue of some kind. Tell her to keep her eye on it (you, too, if she'll let you); if it doesn't get better in a week or so; or certainly if it gets noticeably worse, please have her see a doctor, OK? Good luck - PJH
This could be chafing or irritation, especially if she has just recently started wearing a bra, or has a new one. Since breasts are rarely the same size, a bra doesn't fit the same way on both sides. It seems less likely that it would be an infection, but it might be. Think about how alarmed you would be if she had this same symptom on her tummy or leg and act accordingly. It sounds like she has had this for less than a day, so I'd suggest watching to see what happens. Of course, if she develops a fever or swelling, call the doctor right away. If it hasn't improved in a few days, give the doctor a call.