Help !!! Please

Aaliyah

Today is cycle day 17 and is my ovulation day and out of nowhere I’m bleeding it’s dark but the bleeding isn’t heavy I’ve never experienced this before can anyone relate to my situation if so can you try and help me understand what’s going on I don’t get it today’s the last day of my fertile Window and all this week my ovulation test has been positive and I’ve been fine then today i noticed bleeding 🤷🏽‍♀️ I’m very unsure of what’s going on please help me