Welcome to the Forum  it will be my pleasure to comment. this was q virtually no risk contact.  Even if your partner did happen to have syphilis, receipt of oral sex (scrotal licking or analingus) carries negligible risk for syphilis (or other STI) acquisition.  Further, in your specific case, the fact that would were taking amoxicillin at the time of your exposure would have prevented infection.  Finally, even if you had been in contact with syphilis, your course of doxycycline would have also prevented syphilis if exposed.

I see no reason at all for concern.  In fact, give the history that you have provided, I probably would not have suggested testing in the first place and I certainly see no reason for additional testing at this time.  You are in the clear. EWH  

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Thank you Dr hook. This is very helpful. I have been following you and dr handsfield for some time (including at medhelp). Very helpful work. 

Thanks for your thanks.  I'm pleased I could help.  EWH---

Dr. One last question. You said that the fact that I was taking amoxicillin would prevent the infection but I also know that amoxicillin is not the antibiotic of choice for treating syphilis, is it not?

Amoxicillin is not the drug recommended for Syphilis treatment but all penicillins have activity against the bacteria which cause the infection.  Further, there were small studies performed years ago I which amoxicillin was used to successfully treat Syphilis.  You have nothing to worry about, for ALL, of the reasons mentioned above.  EWH---