What could be cause urinary obstruction with inflammation?

Hi doctor,

I have had pain on the tip of my penis for a few months now. I got tested for STDs, there is no STD present. I got tested for a urinary tract infection, there is no bacteria present and no sign of an infection in the urine samples. I also got tested for a mycosis, there does not seem to be a mycosis present. A doctor prescribed oral fluconazole to be taken for three days straight with a local application cream to be applied in the tip of the penis to treat a possible mycosis, but the symptom persists. I have had trouble ever since my early twenties, the urethra does not completely empty itself and continue dripping a few drops after micturition. I have had issues with skin related problems because of this dripping between the scrotum and the left leg. I managed to solve this problem years ago by keeping the area as dry as possible. I wonder if it could be caused by urine getting stuck near the exit and causing inflammation of the inner walls. I did notice, by looking inside that, urine does get stuck there, not exiting until the beginning of the next micturition.