Before telling you the infections you were exposed to, i would like to let you know that antibiotics should not be taken without medical prescription, as they could be not the solution you need and also bacteria could become resistant as a long term effect of the incorrect use of these medicines.
You had unprotected oral sex, which exposes you to herpes, syphilis and gonorrhea. You should test as follows:
-3 weeks after the encounter, for gonorrhea.
-6 weeks after the encounter, for syphilis.
-3 months after the encounter, for herpes.
All the best.
Maybe, but doxy doesn't cure any of those things. Stop taking it. You also wouldn't see symptoms from an STD the day after exposure. The soonest is 2-3 days.
Make sure you are drinking plenty of water, stop the doxy (if you have something else going on, the doxy could mess up your test results), and if you still have pain in a day or two, get to a doctor.