He should definitely get it checked out. I had a problem a few years ago where my testicles began to ache. Soon my abdomen and lower back hurt. I went to the doctor and found out that I had epididymitis. They gave me antibiotics and anti-inflammatories and it went away. Then it came back about a year later. Same thing...meds and it went away. Now it comes back every few months ago only as achy testicles. The doc said I may have developed a case of chronic epididymitis. Epididymitis is the inflammation of the epididymis which connects the testicles to the urethra. It can occur from an infection which was originally what my problem was but now for some reason the epididymis becomes irritated and sore often. I'm not saying this is whats wrong with him...but he should have it checked. It could be lots of things...or it could be nothing.