Bbt change from sickness?

I noticed a big drop in my bbt. I was wondering if not feeling well can change that? Yesterday I started to become very stuffy so I had to breathe out of my mouth all night and this morning just taking my temp was hard because I had to keep opening my mouth to inhale and exhale while trying to take my temp. I am ttc so I know it's supposed to drop before af as well. Glow says af is due tomorrow but it's been very wrong on everything my other apps say af 10/10 or 10/11. Could it be from breathing through my mouth or af or both?