Did you confirm a MC through your Dr ? You very well still may be pregnant. Are you having any symptoms ? Also know that woman can bleed during pregnancy... It's very unusual and Dr's don't know what exactly causes it, but it can happen.. A friend of mine had her period her entire pregnancy with all 3 of her kids and their healthy and happy.
It could mean two things...one, you are still pregnant and you didn't actually miscarry or two, you miscarried and the hormones need time to completely leave your body.
You can either be pregnant, or the hCG levels in your body haven't dropped below 5 and are still high to give a positive. See a doctor for a blood test.