penis head midly painful, no obvious damage/infection

It's been about 6 months, my penis head midly hurts, not from personal "abuse", there's no signs of infection, no damage, no discharge, no red patches ("down the pipe" or external), I feel 100% ok, no real pain when peeing just sometimes a mild sensation, I can't figure out what's the cause.

All I can think was at that time I was "hit on" and got sucked rather too hard, I had to stop them after about 40 sec. I thought I might have caught a STI from their mouth. I did a home chalmidya test, all is ok.

I could go to my local GUM clinic but the last time I went the Doctor was rude and insulting, my own Doctor tells me go see the GUM doctor for all sexual matters.

I'm 58 in very good health, no drugs or anything, really boring person except I'm in demand for the afore mentioned.