As it turns out, my cat has a slipped disc that, when it affected her
the first time, popped back into place. (Hence the ensuing three months
of unaffected leaping, stretching, and otherwise normal cat movement.)

The vet injected an anti-flammatory medication and is considering
prescribing something long-term depending on the outcome. Since we got
back on Friday afternoon she hasn't hesitated to leap short heights --
such as the twelve or so inches from the floor to the couch -- but
hopping onto the bed still causes her heretofore unwitnessed
hesitation. The vet wants me to call on Monday to provide a progress
report.

The area of her back I mentioned in my original post is, for the time
being, not painfully sensitive to touch, which is a relief. Her
appetite is healthy, and she's using the litter box as often as ever.
(The vet mentioned if the pain were severe enough, she'd noticably
reduce the number of times she'd go to the bathroom so as to avoid
holding that position if it indeed caused excessive pain.)

And the new vet is a nice guy with an admirable bedside manner. He even
kissed her head a couple times when he was performing a physical exam,
a rather lengthy process including much squeezing and pressing, which
caused me a tinge of anxiety knowing the possibility existed her back
pain was manifest in other parts of her body.