Very low risk for such a brief event.
Unprotected oral sex on a female has some risk, but it's much lower than that on a man. If your partner had a syphilis sore, you could get oral syphilis. Syphilis is uncommon in most places, though. You could possibly get oral gonorrhea, but it's far more unlikely when giving oral to a female than a man. The treatment you got for gonorrhea would cure it.
I would have advised you against getting treated for just a few seconds of unprotected sex. You probably didn't need it, but that's done now. In theory, you could be at risk for any STD since you had unprotected sex. In reality, 10-20 seconds probably isn't going to transmit anything.
I wouldn't worry at all if I were you. Is there a reason you're so concerned? Is she particularly high risk? Do you have a regular partner you're worried about infecting?