Progesterone for a couple of day's

Hi everyone, well my doctor just put me on progesterone yesterday. She told me las week my progesteron was 17 and yesterday it drop to 12 now i have to use it for a couple of day. I only have 4 weeks and 6 days i'm scare because today all day i been having light cramping i don't know if this is normal. And they only see the sac im just praying that everything comes out good when i go back on tuesday. Has anyone has gone through this?