PCOS, sex causing period to start?

Hey ladies! Serious question: has anyone else ever had their period start after sex when it technically shouldn't have for another week or so? I have PCOS, so my periods are not always occurring at the same time each month. But this scenario is weird to me because very rarely do my periods start EARLY! In fact they're typically always "late" (not sure if periods count as late with PCOS). Anyway, this is actually the second time this has occurred, the first time this happened was months ago BEFORE I knew I had PCOS. I actually got a positive ovulation test, tried to take advantage of that positive and then had my period start the next day ☹️ This time I didn't do an ovulation test so I'm not sure if that's a common factor in this issue but I'm just curious if anyone else has experienced this. I have an appointment with my doctor next week so I'm going to bring it up then but it's nice to know if others experience the same things as I do. Thanks in advance! 😊