I have swollen and discolored penis. What is it?

Hello doctor,

I have been frequently dealing with a red, swollen meatus as well as discoloration on the penis glans. It first began after unprotected oral and vaginal sex with a one-night stand three years ago. About two weeks after the original encounter, I began experiencing a burning sensation while urinating along with itching of the penis glans, red swollen meatus and discharge. While the symptoms remained the same, about two weeks after having the STD test, I contracted strep throat and was given the antibiotic Azithromycin. Not only did this clear up the strep but also stopped the itching, burning and discharge. However, my meatus remained red and swollen. I went to my local clinic and the nurse who examined me said everything looked fine. Relieved, I went about my normal life until later noticing a small white spot on my penis glans. The spot was not irritating or painful. However, they did not go away and pretty soon I noticed that the entire underside of the head of my penis had turned a pale grayish color. I then went and saw a urologist who ran multiple urinalyses and did blood work. All tests came back negative, and he told me I was fine and to just stop thinking about it. I had sex with another partner about two years ago and after three weeks of the encounter, she was treated for UTI (urinary tract infection). What could this possibly be with all the tests coming back negative?