Difficult to say without evaluation. Infection should be ruled out, and can be evaluated with a urethral swab as well as urine tests.
I would also consider imaging to look for cysts. Scrotal swelling can also be evaluated with an ultrasound - with things like cancer, thrombosed veins, varicoceles, or hydroceles being possibilities.
I would discuss these options with a urologist.
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.
kevinmd_