Hi SkeletonBoy, Welcome to HealthcareMagic Forum.
How old are you? There are various causes for the Testicle pain
(Testicle Inflammation), Mumps, Orchitis, Urinary Tract Infection
, direct trauma and various others. Kindly get yourself examined by a Urologist
, so that he can examine you thoroughly and rule out the exact cause for your Pain. Apply heat pads regularly and give yourself some rest and stop masturbating for a week until the pain subsides. You will require analgesics and if necessary antibiotics.
Good Luck, Take Care.