When I was 13 I noticed that I had a hard lump under both of my nipples, and had it to about 15-16 but never told anyone. It hurt sometimes but I just went on with my life. I later found out that it is called gynecomastia. My brother now has it, he is 13 and got it check out and the dr. said it was normal. But what I want to know is does that mean that you have a higher than normal estrogen level that is causing that? That is the only reason i can think of that happening, or what else can it be?