Levels still rising after what i thought was a miscarriage

Okay sooo, when i was 5 weeks 5 days i got diagnosed with a 3cm subchorionic hematoma which grew 4 days later and caused many bleeds the er told me "not to be concerned about" my dr told me i was going to miscarry. I chose to wait and do it naturally. After a week of nothing but my regular hematoma bleeds i went to the er for dehydration and nausea and they told my my hcg has still been doubling. I figured it was taking a while to come down. Fast forward to new years eve i thought the miscarriage started and i had another big bleed with a pretty large clot which i thought was baby, i had a check up yesterday and my hcg is still rising a considerable amount. My levels are now almost 100,000 and its been a week since ive been to the er and they told me my levels were doubling still. What is the reason for this??