It's great you're taking such an interest in this. LOL. It can be anything from a small sore spot to your whole nut stinging. If it's nothing serious (as this was) it stops in a few hours or so. But this one time, a few years ago, I was helping a friend of mine with some of his wrestling stuff (the real kind, not WWE), but my nut hurt so bad from that. Apparently, that's why wrestlers usually wear thongs and tight spandex. It prevents your nuts from slapping into your leg.
H-D 