The most common cause for frequent urination of small amounts with urethral discomfort in a young male would be a UTI or a urinary tract infection.
This can either be due to:
Cystitis (infection of the urinary bladder)
Prostatitis (infection of the prostate gland)
Urethritis (infection of the urethra), or a combination of any of the above.
Other common causes would be sexually transmitted infections or even urinary tract stones (in this case possible a stone in the bladder or urethra or even in the lower ureter).
A trip down to the urologist's office is recommended.
