Unfortunately Bert, it could be a huge number of problems, from trapped
nerve, to broken bone/tail, to inflammation to just pulled muscle. Try not
to really disturb him, just in case you don;t make damage bigger
accidentally. It could be even upset stomach, or some other organ
infection.he may have been playing and fell off something and hurt gentle
bones. He would be listless if in pain. But unless the vet ordered
otherwise, do bring him food to where he is, rather then let him wonder to
the dish. Also you could bring his litter tray near as well just for now.

My Charlie doesn;t like having his lower back and tail touched or being
picked up, and does cry and bite if one tries. I believe,  as he was a stray
he was wither hit by a car or hurt by a human, as I'm sure I'm sure I've
seen him around with broken tail limping between his legs. His tail has
healed by the time he moved in here,probably incorrectly,  and vet said
there is not much they could do if that was the case except for braking it
again, but that may not work.

I hope that your kitten has just a minor problem which will be easily
sorted. I know you worry but hopefully x-rays will be able to pinpoint what
it is and how to fix it. I'll cross my fingers for you.

Good luck and do let us know what happens pls.

Gee

ps. you may wanna sent your post also to alt.med.veterinary for more
opinions