What is this irritation on my penis?

[FreakedOut86]

I have had an issue that will not go away and is literally consuming my mind all day. I performed oral on a female in very early March of 2016 and thought nothing of it other than I felt extreme guilt as I have been in a long term relationship. Drunken night with people I should not have been with = dumb decisions. About 2 months went by, and 1 week after working out a lot, I noticed there was an irritation at the tip of my penis at my meatus opening. It was extremely sensitive to my clothing (which had never been an issue) and would not get any better no matter what I did. I visited the doctor 3 times and also a urologist (all starting in May), and all said it did not appear to be an STD. I did gonnorhea and chlamydia urine tests twice, and had a full blood work up testing for all major STD's including HSV. I was initially prescribed an anti fungal cream, did nothing. I was then prescribed a 10 day doxycycline regimen, did nothing. 1 doctor I went to freaked me out because he didn't even look at anything and decided he was going to give me a rocephin shot, 1g azithromycin, and a single dose of metrodonizale (sp?) "just to rule out anything". Seemed pretty unprofessional but I was desperate. My last trip to a doctor ended in a prostate exam which he said was fine, then referred me to a urologist. He examined me and said everything looked normal but could notice a small sign of irritation. Thought possible trauma from excessive rubbing in shorts. Prescribed me a steroid cream (did nothing) and said that there was no way I contracted anything from my encounter. I have spent countless hours looking up this issue and noticed there are many who are suffering from this mystery condition. I even convinced myself that I had Mycoplasma Genitalium (from my "research") and took a 7 day course of Moxifloxacin which seemed like it worked for a day or 2 then went right back to what it was. I know it's not a good idea, but I've tried everything since...mupirocin cream, neosporin, zinc oxide, drank apple cider vinegar, cranberry juice, everything. I used to be very active, which has all come to a screeching halt because of fear of further inflammation, but recently I would sprinkle some antifungal powder in my boxer briefs which seemed to provide me some relief while running around. But recently it seems that was making my genitals so dry, that it irritated it more and last week I actually got a rash on my penis shaft... which of course freaked me out and has me in cold sweats just thinking about it. I don't understand what I have, if I can cure it, or if it even has anything to do with an oral sex encounter. What could this be? Is there any STD that could cause such symptoms from this type of encounter? What should my next steps be? Is there additional testing that needs to be done? I know I need to stop reading and trying to find home remedies to fix an unknown problem, but this has been over 6 months of a constant issue that will not resolve and has not responded to a number of treatments. I'm lost, I'm miserable and I don't know what to do. My girlfriend has no symptoms, and I feel like I've ruined my life and possibly hers if this indeed turns out to be a serious condition. I know there's people out there googling this same issue, and no I don't have any answers, but someone has to know what this is. Please help!

Symptoms:
-Swollen and red irritated meatus
-Sensitive to clothing
-no discharge
-slight itching feeling just inside meatus at times
-meatus really flares up after ejaculation
-aching feeling in left testicle and sometimes groin/thigh
-no difficulty in urinating, but have constant dribble afterwards

-just last week got a blotchy rash on top of penis shaft (maybe due to extreme dryness from using powder?) (were never blisters) went away in 24 hours after applying zinc oxide cream.

Any help or advice would be a blessing!