What's up with my period?

I've been experiencing an abnormality in my menstrual cycle. I've been late for 1 month and i finally got it. It only came for one day though, and after then got it back four days later. It comes down extremely heavy and big clumps of blood come out. Recently a rather huge clump came out, and I'm scared that it might be a fetus. I don't think i'm pregnant but I'm still scared. Please, some advice on my menstrual abnormality.