Almost 9 years in the hobby and I've never experienced what I've experienced my last couple of SPs, 2 out of the last 3 SPs I saw were either starting their period or ending their period.
The first time it happened I pulled out and I was like WTF, fortunately I cummed already but this was the first time seeing blood on the tip of my penis. I don't think the SP realized it and I just went to the bathroom to clean up. I give her the benifit of a doubt considering the blood was bright red so shit happens. I even went down on her before penetration started and I didn't see or taste anything out of the ordinary.
The second time this happened was more disturbing as I went down on the SP I noticed that her pussy did not taste as fresh or clean as I would have liked. But since things were heating up and she was getting into things I just over looked this minor detail and just continued eating her out. Towards the end of the session when I pulled out of her pussy, surprise surprise! This time the blood on the tip of my penis was a more darker red almost purple which logically tells me she did not wash herself properly during her period, thus the bad tasting pussy. She also noticed the blood and gave a sigh as I was turning around to clean myself in the bathroom and rinse my mouth out.
Now it's making me more hesitant when going down on a girl or fingering her not knowing what surprises might happen. But it won't deter me, I'm just hoping this is not a recurrring thing for me as I don't plan on leaving the hobby anytime soon.