Dear Friend, At your age the most common reason for pain in the testicle can be infection or injury. If you have infection then some times it is associated with fever, burning while passing urine and ejaculating semen. If you do some excercise or play then there is a likely hood that you might have injured your self with out noticing. I suggest you get a urine routine examination, CBC, urine culture and sensitiviy and an ultra sound scan of the scrotum done. I wish you a speedy recovery.