I gave a guy a lengthy deepthroat blow job that got rough at times (gagging, choking, etc.). At one point I used a tissue to wipe up and to spit out the excess saliva in my mouth before discarding the tissue and continuing in oral play.
Afterward I noticed that the tissue I used had some traces of blood through it, mixed with my saliva. Not sure what happened or where the blood came from exactly but did anything I engage in put me at risk for HIV?