Spotting on the pill

So I’ve been on the combination pill for about a year now, and I’ve never had this problem before. I started spotting a few days before my last active pill for the month and I don’t know why. It was light brown, sometimes dark brown and red, which I’m guessing is old blood but idk. I think my period started today, but I’m not sure if it’s also just heavier spotting. I also took a pregnancy test which came back negative. I’m guessing it’s stress and a hormone imbalance cause I’ve been feeling super moody and irritable and sad lately cause of work and anxiety. Can someone please provide some intel, I’m just scared something might be wrong cause this has never happened before in the entire year that I’ve been on the pill (taking it perfectly btw).