Bottom line:  Little or no risk for HIV -- testing optional. Somewhat higher risks for other STDs, but still low enough that testing is optional. 

The details:

In Nigeria, the chance your female sex worker (FSW) partners have HIV could be quite low (e.g. if they are escorts, i.e. expensive FSWs by appointment) or quite high for brothel workers, street walkers, bar pick-ups, etc. But even if infected, the average risk for transmission from a single episode of unprotected vaginal sex is 1 in 2,500 -- and it's much lower than that for the sorts of contact you describe. The apparently different advice you found online about transmission risk for cunnilingus (oral-vaginal) and analingus (oral-anal) -- i.e. low vs zero risk -- really isn't different at all. Theoretically HIV could be transmitted (hence "low") but there has never been any proved case of HIV transmission by such exposures (hence zero risk for all practical purposes). So there really is little or no risk at all for your oral-vaginal exposure(s), even with swallowing genital fluids; or for oral-anal, including exposure to feces. Kissing also is zero risk for HIV. (Saliva doesn't transmit HIV. In fact, saliva is toxic to the virus -- it kills HIV.)

The main STD risks for these events were for gonorrhea -- but here too, the chance is extremely low for either oral-vaginal or oral-anal. Chlamydia theoretically is possible, but oral chlamydia is very rare and has never been known to be transmitted by the kinds of events you describe. Syphilis is possible, but also very unlikely. As for your question about antibiotic because of the anal/feces exposure, the answer is no. The highest risk of all for you was for various non-STD intestinal infections, but the large majority of those are viral, and no virus is treatable with any antibiotic.

So as noted above, overall risks are low enough that testing is optional. However, most likely you'll decide to be tested:  most people in your situation are more reassured by negative test results than by professional opinion, no matter how expert. If you go ahead with any testing, have a throat swab for gonorrhea, valid any time more than 2-3 days after exposure (it probably will include chlamydia, which is pretty much automatic with gonorrhea testing); and blood tests for HIV and syphilis at 6 weeks. Be on the alert for symptoms, like a painless sore on a lip or in the mouth in the next 10-20 days (syphilis) or nausea, vomiting and/or diarrhea (non-STD intestinal infection). If no symptoms, just sit tight and wait for the test results. Stay mellow in the meantime:  all these tests probably will be negative.

I hope this reply has been helpful and eases your fears. Let me know if anything isn't clear.

HHH, MD