STD Risk of Unprotected Oral Sex

I am a 40+ male and it has been 25 days since I received unprotected oral sex from a sex worker.   We engaged in no kissing or any other sexual activity.  I have had no sores of any kind except a single large pimple-like sore on my rear end which appeared in about 10 days after exposure and was cleared up after about 20 days.  The "pimple" was painful to the touch but never seemed to burst or ooze.  I assume it was just a pimple.  Noticeably about a week ago, I started having an unusual tingling and slight sensation of numbness in the head and tip of my penis.   Urnination has not been painful but after I finish urinating I occassionally still drip urine and have a sensation that I need to go despite only a drip of urine.  I have looked for but noticed no oozing of anything from my penis except for what appears to be urine although, as I mentioned, it does drip more frequently after I finish urinating.  The tingling sensation in the head of my penis and especially tip of my penis is almost constant these days and I have never had those sensations there before.  

1.  For what STD's might I possibly be at risk?
2.  What STD's (if any) are consistent with my symptoms?
3.  For what STD's should I be tested and how soon after exposure should I be tested for each?
4.  Do my symptoms sound like something you recognize that is NOT an STD for which I should be tested or treated?
5.  Am I correct that I have no risk of HIV from this exposure?
6.  Do my symptoms including the "pimple" on my rear end sound at all like they could possibly be Herpes 1 or 2?  I was tested 2 years ago for both Herpes 1 and 2 and was negative for both.

Your help is much appreciated.  Thank you.

[Edward W Hook, MD]

Oral sex is an inefficient way to transmit STDs.  Of the bacterial STDs only gonorrhea and nongonococcal urethritis (NGU) are transmitted through oral sex; chlamydia is not and without an obvious sore or lesion on your partner’s mouth, the chances of syphilis and herpes is likewise tiny.   If you had gotten gonorrhea or NGU you would have most likely developed symptoms of urethritis (penile infection).  Even if your partner had an STD (any STD and it is likely she did not), most exposures do not lead to infection.  As for your specific questions:

1.  Se above- NGU and gonorrhea.  Either could cause mild symptoms in your penis although no STD causes abnormal dripping after urination.
2.  Not really.  The only exception would be if there is a tiny bit of urethral discharge.  The way to put things to rest is to get examined and either get a swab test (Gram stain) performed on a swab specimen from the penis or a urine test performed on the first part of a urination (either specimen can also be tested for gonorrhea and chlamydia).  For either test, the tests are better if you have not voided for at least two hours before the sample is taken.
3.  Se above- you can be tested now
4.  You symptoms really do not raise any "red flags" for me
5.  Quoted odds of HIV from receipt of oral sex- less than 1 in 10,000.  Neither of us on this site has ever seen a person who clearly acquired HIV in this way although there are a few well described cases.  Your risk is miniscule.
6.  Your exposure was not on your rear end but on your penis.  Unrelated

Hope this helps.  EWH