I hope this finds you well. 

In June I received unprotected oral from another man. Over the Christmas break (and still to the present) broke out with a red face rash. I had a virtual appointment and they prescribed me 100 mg of doxycycline for 10 days(twice daily). That didn’t resolve the rash and then I started getting spots on my toes which freaked me out so I tested for Syphilis on 1/17. The results were non reactive.

 Would the doxy have any adverse impact on my test results? Do I need to retest? Do you think I need to test for anything else? 

Thank you in advance for your guidance. 

Your facial rash was not due to syphilis and is almost certainly unrelated to the sexual encounter that you describe from June.  The doxycycline would not prevent your syphilis test from being positive if you had been infected.  Your facial rash is likely due to something other than an STI acquired in June or from your doxycycline  Similarly, the rash on your toes is not syphilis either.   I would suggest you see a dermatologist about the rash if it is troublesome,.  It is not due to an STI and you do not need further STI testing.  

I would not be worried at all about STIs related to the encounter you describe at this time.  EWH

Thank you for your comments they are very reassuring.  I am scheduled to see a dermatologist in may. 

I know I’m being illogical but I cant help to have anxiety about this encounter. 

The rash is limited to my cheeks. It would be safe to say that I can rule out herpes as well, correct? I’ve been using condoms with my wife but I’m safe to stop at this point?

Again thank you for guidance. Appreciate your forum and expertise. 

I see no reason to abstain from unprotected intercourse with your wife related to the encounter you describe  EWH