If I was you, I'd narrow down the possibilities. Try to eat her when she hasn't showered for a few days. If you got some sores around your mouth, well you probably narrowed it down to herpes.
Also just to make sure, while you're going down on her, bite her labia until it bleeds. She will probably yell at you in pain, fake to be sorry and that you lost control of your libido. Now, use a little sharp object as a knife and when you see some blood, rub the part that is bleeding on her bleeding labia so your blood and her blood get mixed up. That should narrow down AIDS.