Something similar happened to me in paintball. I never got it checked out (which was probably stupid, although I've had physicals done and my doctor hasn't noted anything odd down there), hit my left nut. I was in pain for a couple weeks, although I don't know that it really swelled too much.
Could just imagine how much a ice cold puck that's much bigger than a paintball feels. Since then, I never do any kind of activity in which a projectile can come at high speeds toward me without a cup. One time I forgot my cup, and instead of playing without one, I immediately went to the proshop and bought a new one. If they were closed I would have went home. No way I'm taking that chance.