Saw this was closed, but figured I'd make a quick post to calm your nerves. If you're young (e.g. age 10-13) this is a perfectly normal stage in puberty that a lot of people go through. The lump dissipates in it's own time without any medication or special treatment. Unless it's causing you pain (when not deliberately pressing down on it or sleeping on your stomach) and there are no other abnormalities or discharge you should be fine. If you're truly worried, go see a doctor.