This is kind of an unusual question. At least, I hope it is more interesting that the usual "am I at risk for HIV" questions.
So, I have a small sore on my scrotum. I worried at first it my be herpes, but every sign points to an ingrown hair or perhaps a common pimple. I have bad skin with occasional cystic acne and have had bad folliculitis on my body (mainly my back). So a pimple anywhere on my body where there is hair is not uncommon for me. The sore started as a red painless lump on the front of my scrotum about 9 days ago. I applied a warm washcloth to it and it formed a white head. I popped it and brownish yellow pus came out. It began to heal but not completely and stayed red and swollen so a few days later I did the same thing again. Again, more yellow pus. That was maybe 1 or 2 days ago. Afterwards the center of the pimple was red and raw and bled a little bit. It looked like a herpes sore with depressed center, but again, it was completely painless and solitary (and also looked like a bad pimple). I may go to the dermatologist to have it looked at but I have a feeling it will be healed in the few days it will take for me to go see him. I'm guessing its not herpes as it is: completely painless, solitary, filled with yellow pus, and seemed to come from deeper under my skin.
A girlfriend of mine was coming over tonight, and I was worried about potential STI transmission through a somewhat open wound so I decided to apply liquid bandage (called New Skin) on it to protect it. It is a liquid bandage that you paint over a cut to protect it from dirt and germs and it also contains an antibiotic. I put two layers of the liquid bandage over the sore and let it dry. Later, the girl and I had protected sex (oral and vaginal, both protected). I know that she had been an IV drug user in the past so I was very concerned and insisted she take an HIV test beforehand. We used one of those OraQuick tests you can buy that the pharmacy. Instead of swapping her mouth, she used two drops of blood from her finger. The old OraQuick tests said that blood was also an option, but the new ones only talk about the mouth swap. I have no idea why. I hope blood still works. We didn't do the mouth swab because she had been eating and drinking and apparently you have to wait at least 30 minutes if you had been. Anyways, the test was negative. Of course, I worry about HIV she could have acquired in the past 3 months that wouldn't show up on the test. And I also worry that even though I used a condom, would the liquid bandage protect STI transmission from her vaginal fluid which may have touched my scrotum. Am I at risk?