Idk what to think

This was our first month doing iui, I was on clomid, I used the ovidrel trigger shot, I def ovulated and put out a 22mm and a 18mm. Then was placed on progesterone a two days after iui but for some strange reason my bbt has been dropping over the last three days. I'm 7days from when my period is suppose to start which with being on progesterone normally doesn't happen til I stop it. I'm just worried my temp won't go back up and this will be a failed cycle :( and opinions on what's going on? I'm 10dpo today