Welcome to the NT family. I hope that you appointment for your mother will go well and that you will get some answers. As many of us can attest, at least having an answer to what the problem is is better than going on and not having a name for the pain that you're having.
I was diagnosed three days after a knee surgery-all are shocked as usually it takes much longer for symptoms to develop, but 3 of 4 objective signs can't be wrong.
I wanted to suggest to you that during your mother's period of hospitalization, there could still be opportunities for RSD to show itself. There are many here who developed this disease after needle sticks, blood draws, etc, which I am sure were part of her stay.
Sending my best hopes your way,
Lori Lee