I will list this first, as its most important for all to know.
If you have severe testicle pain, you may have Torsion.
Torsion is where the tubes that connect to your teste twist, and constrict the blood flow to your testicle.
If this happens, you have only a short time to get medical attention before you LOOSE your testicle. Once it strangles, its gone.
Generally if it IS torsion, your on your knees, writhing in pain, crying, and carrying on.
Doctors on the board, please correct me if I am wrong.
Please, guys do not fool around with pains in your groin!
On the lighter side, if it just feels like a kick, it could be the start of torsion, or just classic Blueballs.
Been there, done the blueballs, and have them nearly daily.
I have had that chronic problem since I was 16, and I went to a urologist, and he simply said, You produce more semen than most boys/men your age. You need to jack frequently.
Mine back up so bad, that I get cysts on my testicles, and they get larger if I dont pop.