My Daughter Is 20 Years Old And Will Be 21

My daughter is 20 years old and will be 21 at the end of March. She text me saying she has a lump on here side right where her breast starts. She said it has been sore a couple of months but she is now able to feel the lump when she rubs her hand across that area and she can actually see it starting to protrude a little bit now. She said the lump is about the size of a grape and it does not move when she rubs her hand over it. She wants to know what kind of doctor to see, our family doctor or a OBGYN and do you have any idea what it could be possibly?