Red spot on penis tip STD symptom?

[Liam225]

About 3 weeks ago, I had sex with a commercial sex worker. I have had no previous history of any STI/STD (only had one sexual partner prior).  During the intercourse the condom came off a few times, and I think there may have been a point where my penis was inside uncovered.  I also received unprotected oral sex.  Since then I have been extremely paranoid and suffering anxiety.  Two weeks after the encounter, I developed a headache with chills/night sweats (that lasted one night) and diarrhea lasting a week.  There was a bug going around my colleagues with the same symptoms so hopefully I had what they did. I am also in a foreign country and may have been suffering from Traveler's Diarrhea. Now after feeling normal again (three weeks after the encounter), going on a 3 mile run, and sitting in a dry sauna for 15 minutes I noticed a skin colored splotch on the tip of my penis.  It is very difficult to see (doesn't look like bumps/painless), and I am not sure if it has always been there, but I noticed it upon examination (I have been paying extra close attention lately).  I also have felt tenderness in one of my testicles/groin area, but it could be all in my head due to anxiety/paranoia. Today (24 days after the event), while in the shower, I noticed a red circle on the glans of my penis (a quarter the size of a dime).  It does not itch or hurt.  I thought I may have noticed this a few days ago, and confirmed it today.  It hasn't gotten worse in the past few days, but I can definitely see it when very carefully observing.  Does this sound like any STD?  I am going to meet with a Urologist this week to get tested, but want to know in the mean time if this sounds like anything in particular.  Thanks