Update in Kitty: Boy, you never know!

http://www.democraticunderground.com/116122200

Left my poor kitty at the Vet today for a complete check-up. Never expected what the Vet found.
I thought kitty was sick, maybe a UTI.
Vet called me about 2 hours after I left her.
Kitty is healthy, no signs of infection but:

Upon examination, the Vet found that my kitty cried as she was examining kitty's body. Vet was checking things like bone or other non-infectious problems first. Seems poor kitty cried as the vet was checking her back. Upon further exam, it seems like poor kitty has an injury of some sort to her back. Below the rib cage. Perhaps vertebrae.

Trying the following: Injection of Buprenex this Am by the Vet. Tonight I will give her oral(liquid) Buprenex by mouth, then twice daily for the next 5 days.
She will also have a pill(fun) Onsior (kitty type Advil-ish) for the next 3 days, starting tomorrow. The vets advised me to keep poor kitty quiet and keep her from any exercise. No stairs, no jumping up on furniture etc. Must be allowed to rest and heal back injury.
I hope this is all that is wrong and that kitty is better.

The next step, if she is not better in a week or so will be X-Rays. Scares me. $$$

Love my kitty. I hope she rests and heals. All I can think of is that she walked on the stair railing and fell. She loved to jump up on the rail and then down to the floor. I never liked it and hoped she would never fall. Perhaps she did and that caused the problem.
There is nothing in my house that could cause a back injury. This is all I can thing of.
Hope the Vet is right.