I am 26 year male. Unmarried and virgin. I have a dark patch around the opening of my penis on the glans. I visited a dermatologist who said there is an erosion in the area of the penis opening and is always red. I have had trouble in passing urine where I have to wait longer for urination to start. Urine is usually yellow, less in quantity and acidic (performed lab test and micro analysis, reports are normal). Multiple times I visited the doctor and he suggested Arflox and Sonaderm for topical application, which did not help much. I was also recommended Cystone for couple of months. I feel my urethra and bladder a little warm and irritated from inside (particularly overnight). Urethra seems to swell and penis loses flexibility. My foreskin does not cover my glans completely. Once Rabekind and Urikind was suggested it helped a lot but temporary.

I masturbate usually 1-2 times a week.
For past 4 years I live in a hot and humid place and I have had hyperacidity and constipation trouble. I drink 2-3 liters of water everyday.

What can be cause of irritation in urine?
Can my penis look normal again without redness and dark patch?