Huge blood clot... Help!

So I have had a really weird period this month. I've had two, which is not normal for me. I have been off my period for 4 days and just a minute ago I went to pee and when I wiped, there was a blood clot the size of my hand on the toilet paper. I'm a little concerned because my roommate told me I could be possible having a miscarriage. Any advise?