Why do I keep bleeding heavy and passing clots?

Tiaonia

I seriously took this test yesterday and I see a faint line which looks like a positive to me! Yesterday I was experiencing some cramping. My period was 4 or 5 days late as well. I kept having light pink spotting then it would turn brown. When I woke up in the middle of the night, I went to use the bathroom and I saw red, heavy blood coming out of no where and little clots were passing. It has been doing this all day! I don’t know if my period is on, I’m pregnant, or having a miscarriage?