Thank you for your help. 

I am a 29yo straight Male. 

19 days ago I had a brief encounter with another straight Male of unknown STD status (we met minutes before on Grindr). We both performed oral sex on each other for brief seconds (surely less than 20 seconds), without ejaculation from any of us, but I had a canker sore on my lower lip at the time. 

Since then I've been feeling totally paranoid over the possibility of getting any STD. 

4 days ago I tested for Gonorrhea / Chlamydia; HIV and Syphilis, but still waiting for the results (should arrive in 3 days). 

2 days ago I started feeling a sore inside my cheek, very tiny but painful. It is between upper and lower teeth so chances are this happened from biting, but I can't stop thinking this could be a chancre, since the timing (17 days after the contact) would be a correct match for syphilis. It feels like a canker sore (which I have frequently, and now could happen even more likely, due to the extreme anxiety levels I am experiencing), but until now it is just red, without any extra color (white, yellow, grey). 

My major concern from this sore is Syphilis, specially since it won't be excluded based on the test I took 4 days ago, since it was clearly too early to detect Syphilis. I am aware that Gonorrhea has a higher chance, but the fact that I will be able to exclude it (hopefully) in a couple days brings me more piece of mind with regards to it. 

I am very scared, because I am on a stable relationship and this was my first time ever doing anything outside marriage. I am a very healthy person and really don't want to cause any health damage to my wife. Since that event I've been avoiding any sexual contact with her. 

Thank you very much 

I presume your testing for gonorrhea and chlamydia involved not only a urine test but also a throat swab.  While unlikely (you do not know your partner was infected and most single exposures do not result in infection) unless you also had a throat swab for gonorrhea and, less likely, chlamydia, you have not entirely ruled out the possibility of a throat infection.  Results of current tests for gonorrhea and chlamydia however are conclusive any time more than 4-5 days after an exposure.

The sore on your cheek is almost certainly not herpes as a HSV lesion would appear within 10 days.  Syphilis is a possibility but statistically unlikely.  What you describe does not sound like syphilis and if the sore on the inside of your cheek had been present to more than 2-3 days and were due to syphilis, a syphilis blood test would be positive.

I hope this information is helpful.  If anything is unclear, don't hesitate to use your up to two follow-ups for clarification.  EWH

Indeed my testing for Chlamydia / Gonorrhea was both urine and throat swab. Since I will clear my mind from those in 2 days, my major concern right now is syphilis possibility. The fact that my sore is painful and feels like a canker sore reduces the chance of this being syphilis, am I right? 

Just one final question: if I had oral syphilis would I infect my wife from a penetrative sex, without any contact with my mouth? 

Thank you very much! 

 As I said earlier, if the lesion is due to Syphilis, a blood test would be positive any time 2 to 3 days after the lesion appeared. If the lesion is not due to syphilis, a negative test at four weeks would be very strong evidence that you had not acquired Syphilis although, as I mentioned earlier, some experts, suggest that it may take as long as three months for Syphilis blood test to become positive. Obviously, the longer since the encounter that a negative test occurs, the less likely it is that you have syphilis. Personally, I would consider any negative results more than six weeks after your encounter as being conclusive.

 Sorry, I cannot be more precise, the timing of how long it takes for syphilis blood test to become positive is controversial, because so much of the information on this topic is more than 70 years old.   That said, the chance that you inquired Syphilis from encounter you described is minuscule. EWH.