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An injury to testicles can form a hematoma, which can become infected. It can cause scrotal muscle and nerve injury. Apart from this sometimes it can cause orchitis or infection or inflammation of testis. Only orchitis will present with some redness and swelling in the testicular area. Pain in testicle could also be due to infection, like prostatitis and epididymitis. Get a culture sensitivity test for both semen and urine done. Also it could be due to referred pain of kidney stones. An ultrasound of the lower abdomen will be able to rule out kidney stones. An ultrasound of the testicles will diagnose cancer, varicocele and spermatocele, hematoma etc and should be done.
Since I do not know the related conditions you may be having, nor is a detailed history or diagnosis possible on net, I have listed the various possibilities that should be looked into. Please consult an urologist to run tests and examination to clinch a diagnosis.
i went to the dr they did blood test but nothing was found even my urine t est showed nothing.the pain still exists what should i do now? i dnt know how to approach this problem as it is very embarassing.