GUYS. I know this is soooo gross and I was soo embarrassed but a light period started while my bf and I were doing oral. I didn't expect it because it's a week early and it wasn't on my undies before taking them off. Anyhow, we noticed the blood after we were done having sex. I thought maybe it was just from penetration but my bf admitted that I tasted weird, but didn't want to say anything bc he thought maybe I was just a little sweaty or something. I can't even begin to explain how mortified I was 😭 BUT my bf was chill about it and told me "it's okay, you didn't know, and it's completely natural". 
Although I felt so gross in my head I was thinking booooy ;) you just wait until this period is over. His response to it all just made me love him 100x more.