Hi Doctor,

I really appreciate your help on my question.
I have always been safe when it come to sex until this event. I met a female professional escort from Montreal a week ago. We didn't have any traditional unprotected sex. The only thing that I did was, I asked her to lie down on the bed facing her butt up. I then rubbed my penis between her butt cheeks horizontally and ejaculated on the top of her butt.
I did not notice and fluid on her butt cheeks. My concern is that whether she may have had any semen or vaginal fluid on her butt cheeks from the encounter she had before me (in invisible form). She uses the same bed sheets for all the customers. If there was some some sort of fluid on her on her butt cheeks, is there any chance for me to be infected with HIV by providing a direct root via rubbing and ejaculating on those invisible fluid spot?
After a week on this happened, I have got a sore thought and felling lethargic as well. I know this is a relatively low risk activity, but desperately need the experts' opinions.
Thanks so much.
John