What Causes Itchy Scab On Nipple Of A Child?

My 9yr. old daughter has a small scab over her left nipple. She went swimming a few days ago and said both her nipples seem to sting while in the water. I thought maybe her skin was dried out from the chlorine and had her put on some Aquaphor healing cream. I had not heard anymore complaints from her until tonight when going to bed she mentioned that her left side now has a scab. She said she had remembered scratching both sides after being in the pool as well and that the other side seemed fine now though. Should I take her to a doctor to have this checked out or wait a few more days? Also, about 3 months or so ago she had a little round lump in that same left breast. I was going to get her in with my doctor since her pediatrician was Male and she wanted a Female doctor. Mine was backed up with appointments, and the lump seems to have subsided, so I m guessing that may have been hormonal. She does seem to be early with her growing in more teeth at this age and hair on arms and legs, so I m wondering if this may be hormonal changes she is going through. And, no...by no means is she sexual or anything like that. Thanks for any help or suggestions.