While playing with my 15-month-old daughter yesterday, I noticed a soft, moveable lump about the size of an acorn in her right breast. It is under the skin in the nipple area, it didn't hurt her when i was feeling it trying to figure out what it was. She doesn't have a fever, or any other symptoms and the skin and nipple are both normal color. It doesn't seem to bother her at all. I have an appointment set up to check it out, but i'm so worried, does anyone know what this might be?