Do you have a reason to test for HIV or other STI's? Have you engaged in unprotected sex? If not, this COULD have something to do with your recent infection or the medication you took. I would strongly advise you to contact your doctors office and let them know what is happening. They may tell you it's very common, nothing to worry about and will soon go away or they'll have you come in for testing. We can not diagnose you and I believe this is something your doctor should know about. I wish you the best.
Okay, going deep here with the personal stuff. Do you mean like you have vaginal creamy discharge when you have a bowel movement? To be honest, lots of people do. Leucorrhoea is one reason. That's a big fancy word for a whitish, yellow discharge. It happens when our estrogen is a little out of balance. It has happened to me. Joy. You see it during a bowel movement because you are bearing down. You can call your health provider now to report this and be seen or mention it on your next physical or pap smear. Good luck
And I see you are afraid of HIV. HIV is one of those things in which symptoms rarely a means to diagnosis. You would only know about HIV if you take an HIV test, and you also have to have a true risk for HIV which is very basic, unprotected vaginal or anal sex or if you share intravenous drug needles with someone. Otherwise, HIV is not a concern. As to other STD's, again, it would depend on your activity and you can be screened by your ob/gyn or at a clinic. All sexually active adults should be periodically screened in my opinion. Good luck