3rd miscarriage?? help!

hi, i've lost two babies, but the first was a stillbirth and the second was early but i never bled i had a dnc after an ultrasound couldn't find the baby's heartbeat or anything. now as you guys know, i had four positive tests but the lines were very faint, and then all the sudden the tests were all negative even the one from the doctor that was a blood test. so now here it is two weeks later that i'm bleeding a very heavy and painful period, and there are a lot of black clots (not to gross anyone out) so i'm just wondering if this is another miscarriage or if its just a very bad period. i'm not sure if it would take this long to bleed if it were a miscarriage, but then again i've never had one like this i've never bled before. anyone have any opinions?