Clay like blood.

So, first things first my period was two days late. Btw, i believe i had an ovarian cyst. Anyways, I wasn't worried about anything in regards to pregnancy. Then my period came and my cramps were worse than usual. I was laying down most of the day and it had seemed that my period suddenly stopped until i went to the bathroom and a lot of blood came. So, resume.. Then today, i went to change my pad and it was like tar colored clay was on my pad. Pleaseeee hlp. Thanks in advance.