Possibly Miscarrying

Ashley • Miscarriage 2/2018* Rainbow baby due 9/2019🌈❤️🥰

I went to the doc these past 2 weeks and my first week I had blood work An my hcg was 145 and the next week my hcg was 331 An I am super early like 3 weeks and he said I could be miscarrying. What do I do if it’s not a miscarriage An he is telling me it is just by my hcg levels?? Anyone have this happened? I’m at the doc now upset An don’t know :/