Severe groin pain is often due to either epididymitis or orchitis. The two conditions are closely related and can occur in tandem, at which point the condition is known as epididymo-orchitis.
Epididymitis is a condition in which the epididymis, the coiled tube which stores and carries sperm at the back of the testicle, becomes inflamed. The condition can occur in males at any age. Among the most common causes are bacterial infections, including sexually transmitted infections such as chlamydia and gonorrhea.
Orchitis is a closely related condition in which one or both testicles of your testicles are inflamed. Again, a bacterial infection is the most common cause. That can include sexually transmitted infections, and in some cases, orchitis results from the mumps virus.
Both conditions can cause pain and affect fertility. Epididymitis and orchitis can become chronic conditions, and in some cases, the cause is never fully determined. While medication can treat infections, soreness can persist for several weeks.