Rising hcg after miscarriage

So about 4 weeks ago, at 6 weeks pregnant I

went to the hospital for spotting. My OB had

said to go to the ER if I spotted because during

an ultrasound they didn't see anything. So they

were suspicious of ectopic. At the hospital they

ran HCG levels, and it was at a flat 10. A week

prior it had been at 6,000 so the Doctor said

this would confirm a natural miscarriage and not

ectopic. So I went home. Over the weeks my

blood was brown & no clotting, just slight brown

blood. Now, 4 weeks later, my OB took out

blood just to be sure my HCG was back at O,

and they called me urgently saying my HCG

went back up. They schedule me tomorrow at a

Labor & Delivery office to be further examine

and I'm freaking out. I'm so scared

something else is going on and I have no idea

what. Any ideas?