What Causes Extreme Pain In The Testicles?

Ok- for a couple weeks now I have been waking up feeling as though I have been kicked in the testicles. Not the doubling-over type pain one would have initially- just that dull, annoying pain one would have after the fact. It has become a little difficult, to sleep- or simply- arranging my testicles while I sleep has become something I'm now conscious of, where as I never had to think of it before. Urinating does not help or hurt, and I have no problem doing that. Ejaculation does not hurt. I have tried to do a testicular examination, and nothing seems wrong, and they do not hurt to the touch. I thought wearing boxers would help but it does not- however, boxer-briefs actually feel better. I have not had any unprotected sex with strangers- I haven't even had protected sex with strangers. I had a hernia examination in February and it was negative(physical for a job). Any ideas?