Thank you for replying! I will definitely be taking her to a vet ASAP (it's just a holiday and I'm anxious so I thought I'd get some other opinions).

Her head shape is a little odd. For a while, she was doing some nose-rubbing on the lid of her enclosure. I haven't noticed it a while (I rearranged some things and added some more clutter), but she does have a bit of a bump and some shiny scar tissue on top of her nose. I do believe that the puffiness in the neck/ jaw is just her trying to pull away from me holding her. I've attached another photo where I'm not holding her so you can see.


I was also concerned it could be an RI. However, I have not noticed any audible wheezing and, although her mouth is pale, I did not see any mucous when she opened it.
She ate last night, and her behavior has not seemed out of the ordinary. She seems alert when I take her out (lots of tongue flicking and her body doesn't feel weak or limp). It's a bit of a puzzle!