Can HIV Be Contracted Through Contact With Menstrual Bleeding?

Hi, I have been to this strip club a couple of times and was there yesterday evening. During one of my extended lap dances with a stripper (~15 mins) or so, she vigorously rubber her private areas (vagina and ass) wearing a flimsy thong over my private area (penis) while I was wearing a khaki and underwear. She even grabbed my penis over the pants and rubbed it, till I cum. I have read a lot of posts and articles regarding lap dance being no risk activity. However when I returned home, I saw that there were some red fabric or marks all over my pants. I am not sure if these are blood marks, as there is no single strain but more like my khaki cream color fabric has red stretch marks in that entire area. I am really concerned if the stripper was having a menstrual cycle and her blood did come in contact with my pants leaving those red stretch marks. I am a big fan of your website and truly appreciate all the good work you guys do. Please let me know if you see this as a reason for concern.