sharp, temporary pain in balls and side

Hi. I'm nineteen. For the past couple years I have gotten, on rare occasions, this pain in my left testicle, even more rarely accompanied by a pain in my side. Specifically the pain is on the left side of the left testicle. It can be pretty sharp sometimes, but never enough to make me double over or anything--it simply makes it harder to walk when it's there. Strange thing is, if I drink some water and sit down for a few minutes, it usually goes away. I haven't felt any bumps on the testicle that might indicate cancer.

Any ideas about what this might be? I've thought in the past it was no biggie, and at times when I thought maybe it was I felt reluctant to see a doctor about it. What do you recommend? Thanks very much for considering this.