Miscarriage?

So I think I'm having a miscarriage. My period was a few weeks late and I was going to get a pregnancy test and started my "period" but it was weird. All of a sudden I was having horrible cramps on my sides and toward my back. And went to the bathroom and there was a huge amount of blood which isn't normal for just a period of mine. I've been bleeding a lot for the last 3 days it's not gotten any better and I'm having awful cramps. Does this sound like a miscarriage? Should I go to the doctor. I don't really know what to do.