As far as I know I am not pregnant nor have I ever been, but I bleed almost constantly. Last year I bled for 4 month and this time I started my period normal it went to spotting as it should have but now Its clotty and bright red and it has been five days since the heavyness started. Could I have had a miscarrage?

Your history is most definitely NOT normal nor is it healthy. You need to consult with a Physician.

Constant bleeding could be something serious.