I have just noticed a small lump under the skin of my penis shaft. More near the top towards the head. It is not a pimple or from shaving. I am 23yr old. It feels like a cyst that will move around but stays intact with the under skin. It is more pronounced when erect since I'm guessing the shaft is harder and pushes the lump up. It will get a little sore with intercourse. I do not recall if this has happened before.