Huge drop in bbt today? Why?!

Usually my temps are between 97-97.5 with some lower temps here and there I think due to having a low room temperature and I get cold. Well the last two days I’ve been on vacation in a new room but I don’t think it’s overly cold in here, but my last two temps have been lower. Today was a huge drop! I’ve never seen my temps so low. What could cause this? I haven’t ovulated yet and I’m on cd 32. I have irregular cycles.