Progesterone drop?

Hey ladies, I’m over 35 and I have had 3 miscarriages.

I’m currently 4 weeks and 6 days pregnant. This past week my progesterone dropped from 27 to 18 then back to 22. My hcg levels continued to rise as expected. I have been prescribed progesterone suppositories ever since I found out I was expecting but still had a drop from 27 to 18. Do I freak out ? Anyone has been through a similar situation? Thank you.