What Causes Passing Of Blood Clot During Periods After Miscarriage?

I have had 2 misscarriges in the last 4 months and i came on my period this morning and i had a very large blood clott? can it be from the last misscarrige i had when i was 8 weeks pregnant ? I am trying to get pregnant so im abit concerned wether or not its from the last misscarrige or wether i am actually having one.