I am a 15 year old boy, and in the last few weeks have discovered a small lump on the inside of my penis. It I located on the left side just above the middle. It is very noticeable when my penis is erect however, it is very hard to locate when not erect. It seems quite hard when erect, but I feel no pain or real discomfort. I am feeling pretty worried about this, and would be grateful for some help.