Lucy seems to have enjoyed her time off. I've been doing a lot of ground work with her so that she's not just sitting around, and tonight we tried a jump chute! She did great!
Thanks for all the helpful suggestions and ideas regarding her mouth issue. I looked in her mouth (the best I could) and didn't see anything abnormal. She's not sensitive to her cheeks being poked or prodded, even behind the eyes as BeBe suggested. I got brave and tried pushing on her gums and didn't feel any bumps or get any kind of reaction from her, so I don't think it's a wolf teeth issue.
She just turned six and had her teeth floated in November, and it was a very routine, straightforward float. The dentist didn't find any abnormalities, but she is floated every six months on a schedule to keep up with the changes in her mouth, so she tends to be pretty easy to maintain.
I am going to ride her tomorrow and hopefully she will be ok! If not, the dentist will come out early next week to investigate.
Here's some video from tonight: