We took her to the vet and he thinks it might be feline neuropathy related to hyperthyroidism. That's usually something that comes with feline diabetes, something she definitely does NOT have. But in rare cases, cats with hyperthyroidism can get it too. Right now we are just waiting for the lab tests to tell us, hopefully, exactly what is wrong with her.
She is resting now, on a bit of pain medication. So maybe it will be all okay. We just don't know. She is getting pretty old.
There should be some kind of offset for those of us who don't have children, and who never wanted children. Our animals should be allowed to live for twice or thrice as long as normal. It's only fair.
___________________________________________________Note: Remember to play the Badgerdaddy Trivia Challenge every day. Fingers crossed...