What Causes Large, Red Lump Under Penis?

Hi, i am a 14 year old kid. I have noticed a rather large red bump on the under part of my penis about 2 inches away from my scrodum. Something has happened like this before where it wad a small with bump on the top of my penis. It went away eventually and i didnt think anything of it. I am starting to get a little worried. I have not had sex before but i have had sexual moments including my hands. I dont know if this is relevant or not. Please let me know what is wrong thank you