miscarriage?

Carissa
Been feeling nauseous for the last couple of days after throwing up once. On top of it i've had these horrific stomach pains that are sharp and then go away but come back randomly. Today i woke up with cramps and back pain which wouldn't make sense because my period doesn't start for another week and a half and it's always right on. I got up to go to work and had dark looking brown blood in my underwear and bright red blood with chunks of dark blood and some clots coming out of me. The pain is insane. I'm worried that i'm having a miscarriage. Doc hasn't called back yet so i'm looking for some advice or opinions.