WHAT THE HELL

So, I took a test just for the hell of it. I’m currently on my period but I had a test left from before I started and it was screaming my name, wanting me to take it. So of course I did. I just thought, oh it’ll be negative, I’m on my period so I can’t be pregnant. But then a line shows up???? What the hell could it be?? Could I be pregnant or is it something else? I took tests before my period started and they were negative. My period usually lasts a full 7 days of heavy bleeding but I’m only on day 2 and the bleeding has almost completely stopped. Anyone know what it could be?