As the title speaks itself, i've got a lump really deep-under shaft's skin, it's kinda close to the urethra, in the middle of the penis.
When i am flaccid it's half (or less) the size of a BB and it's very soft, like a vein.
When i am erect it's getting a bit bigger, and thicker; like it's filled with blood.
As soon as the erection goes off, this little thingy, turns back to the original size.
*It is not a STD for sure.
*18 years old.
*Been having that for a long time ranging from "ever" to 1 year(even though my paranoia makes me think it appeared right now).
Any idea what this could be?
Thanks in advance.