Dear Doctor,
I have a lady friend who is in an open relationship and has multiple partners. About 5 weeks ago we ended up being together one night. We performed masturbation and oral sex on each other without protection. As we were a bit drunk, I penetrated her without a condom, but we immediately came to our senses and I pulled out. I must have had contact for about 15-20 seconds. I ended up putting on a condom and then we had vaginal sex. About 4 weeks ago we got together again and we had vaginal sex but this time with a condom from the beginning. We also performed masturbation and oral sex on each other, again without protection. In both cases the condom was intact at the end.
I have been of fine health since then although I did have a bout of diarrhea (mostly likely because I had had a lot of bad food the day before).
I wanted to know what I my chances of having HIV or any other STI? My lady friend insists she always practices safe sex with all her partners but I know I cant take her word for it.