I would evaluate the testicle for varicoceles, cysts, masses and infection (epididymitis). You have already been tested for prostate infection with a normal prostate exam and PSA.
I would obtain a urinalysis to evaluate for any possible infection, tests for STDs such as gonorrhea and chlamydia and pursue a scrotal ultrasound which can look for cysts or masses.
If those tests are negative, you can consider anatomical abnormalities such as a urethral stricture which can also cause pain. This can be diagnosed via cystoscopy.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
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