I Am 9 Weeks 6 Days Pregnant. 2 Days Ago

I am 9 weeks 6 days pregnant. 2 days ago i went to the bathroom and noticed when i wiped that there was dark redish brown blood when i wiped and that was the only bleeding I had. I called doctor who ordered a hcg level test. That test said i had 37,340 as a level. 2 days later I had another test done which stated my level was now 43,780. Doctor called and told me I am having a miscarriage. But how can they conclude that if levels are going up and they havent done a ultrasound yet? Please help.