I woke up a few days ago and I noticed what I thought was a zit at the crease between my leg and my crotch, at the same height as the base of my penis.

The supposed "zit" feels hard, is a little smaller than a grape, and hurts a little when I press it or squeeze it.

There is no head, and the skin doesn't look too disturbed. How can I tell whether or not this might be a tumor? Should I just go to the doctor?