Progesterone levels

Been taking progesterone because I had a previous miscarriage before I had my son. Approx 7 weeks along now. Doing bloodwork each week to check levels. HCG they said looks great but they told me yesterday my progesterone went from 25.5 to 18 and so we’re going to recheck on Monday instead of Wednesday this coming week to make sure it goes back up. My son has been in the hospital so for 3 days (Sunday-Tuesday night) when I did my progesterone I was up and down all night taking care of him so I don’t think my body absorbed as much. Is this normal?? I don’t go for my ultrasound and check up until the 17th.