Hcg levels increase slowly?

Im 6 weeks and 6 days now .. but i had a scare this week with my pregnancy so i went to the er on tuesday and so i got my hcg levels checked and it was 41,000 and then two days later it was only 53000 .. one of the doctors at the er told me i’d probably have a miscarriage within a week .. i’m so confused and i can’t really believe what he’s telling me because i feel like everything is fine.. does anyone know if slowly increasing levels are okay?