Epididymitis occurs when there is inflammation of the epididymis (a curved structure at the back of the testicle ).  This condition usually presents with gradual onset of varying degrees of pain, and the scrotum may be red, warm and swollen. It is often accompanied by symptoms of a urinary tract infection , fever, and in over half of cases it presents in combination with orchitis .  In those between the ages of 14 to 35 it is usually caused by either gonorrhea or chlamydia . In people either older or younger E. coli is the most common bacterial infection.  Treatment involves the use of antibiotics.