Infection should be looked out for. If the urinalysis is normal, I would be tested for STDs, including gonorrhea and chlamydia. This can be done via a urine test.
If the symptoms continue, you can have the prostate evaluated via a digital rectal examination or consider a cystoscopy to ensure there is no anatomical abnormality present (i.e. a urethral stricture or polyp).
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.
Kevin, M.D.
Medical Weblog:
kevinmd_b