I am 20 years old and I am a virgin, so this is probably not an STD. About 1-2 months ago I noticed a small lump on the right side of my penis shaft during masturbation. I mention this because it seems like the lump is only visible while the penis is fully erect with added pressure with my hand. It is a hard lump while my penis is fully erect, but I can barely feel it or see it while it isn't erect. The hard lump is around 2 - 3 mm in diameter, although I have not measured with a ruler. It appears to be able to slide around under the skin and does not appear to be attached to the skin (I am not sure if I determined this correctly). The lump raises around 0.5 - 1 mm in height while the penis is fully erect, it may be the same size while flaccid but it is very difficult to tell. I'm not sure if this bump is growing in size or not - sometimes it seems to have shrunk, other times it seems to have grown, or maybe it's all in my head.. I don't really know for sure. On two separate occasions while high on pot, I have had a split second of sharp pain come from this general area, I don't know if it was in my head or not and I don't recall getting pains from this area while sober. In terms of tobacco, I was a semi-heavy smoker for only about a year and have recently quit (I read somewhere that this is related).

Please help.. and thank you. Going insane here