I have a problem with my penis it is paining on the side of left testicle

Epididymorchitis: Pain in the testicle is a common reason why men come to the urologist. It may be caused by inflammation, known as orchitis, or epididymorchitis (if it involves the top of the testicle). Another reason could be torsion, or twisting of the testicle. Less common reasons are kidney stones, other infections. You should be evaluated by a urologist.