(She has a regular vet appointment coming up very soon, and this isn’t a veterinary emergency. Don’t worry.)
My cat has suddenly become unwilling to walk on the floor. She jumps from chair back to couch, and will climb stairs if absolutely necessary, but doesn’t want to jump down. She was even unwilling to get on the floor to drink from her water bowl (but she will jump down to eat food - it’s in a different place).
I picked her up and played with her paws a little bit - she didn’t yowl or snap, so it’s not that her paws are sensitive. She jumps acrobatically from high spot to high spot, so I don’t think she’s having hip problems that make jumping from the chair to the floor hurt any more than jumping from chair to chair.
I realize that all cats are weird, even for a cat. Why is my cat suddenly afraid of the floor?