Had a positive test but confused.

Courtney
Well I took a test an it came out positive so call my doc to set an appointment. So I went to my appointment last Monday an he told me that I was 7 weeks 3 days but we couldn't find no baby nor heart beat. So he said he believed it was a moral pregnancy. He sent me to the hospital the next day and they told me that everything looked fine still to early but didn't say if it was a baby or not. I never heard of this an very scared now I have brown discharge every other day and got to go see him tomorrow. But I forgot last Tuesday during the sonogram he seen a yolk sac. I don't know what's going on. Do anyone know what might be going on