It would be difficult to come up with something different without examination, considering you have already been to several physicians.
There are cases of prostatitis that is very difficult to diagnose and treat. Despite what the previous urologist said, I would further investigate this. A transrectal ultrasound can be considered to image the prostate for any signs of an abscess. If this is present, it would need to be drained as antibiotics will not be helpful in these cases.
The other consideration is that there is no infection present. Conditions like a urethral stricture or urethral polyp can cause discomfort in the tip of the penis. You can consider a cystoscopy to evaluate for these possibilities.
These options can be discussed with your personal physician, or in conjunction with another urology evaluation.
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