Hi, My daughter (18) has a very small lump that seems to come and go under her left shoulder (front of body, not back). It s less than 1/2 inch long and maybe 1/4 inch wide. She says it stings a little when you touch it, but there s absolutely nothing on the skin s surface. It was there a few days ago, then disappeared and today it s back, and there seems to be another one parallel to it. Any suggestions as to what this may be? I feel that if I take her to the doctor they re going to have no idea... so I might as well do a lot of homework first. Thanks!