Pandora is doing well on her antibiotics (even if she doesn't much like the taste of them), and the v-e-t just called with her bloodwork results -- NO hyperthyroid, and actually no problems at all. Her bloodwork is very good for a senior ladycat. Mum is very relieved.
Thank you all for your purrs and grrs. We know it has helped. :)
ETA: The vet thought Pandora might be hyper-t because she is so small and skinny. But she isn't, and mum is glad.