Today has been terrible.

I knew something was wrong last night when my 4-year-old cat Cheeky
let out two howls after peeing in the litter box. She hid under the
bed for a short period then seemed normal, jumped up to sleep with us.
When I petted her before dropping off he growled at me--a first in the
two years I have had her.

Got up early this morning and she ate a normal breakfast then jumped
up onto her
nifty new cat window seat she got for Christmas. He jump was clumsy,
and she lay up there crying as if to get my attention. I went to her
and she was purring, lying on her left side, looking like she wanted
something. The scary thing is that her left back leg was shaking
slightly--it was sticking out from under her as they do when they lay
on their sides. I petted her for a while and went back to work. She
jumped down clumsily and was limping terribly, her back left leg the
problem.

Took her to the vet that instant, and of course she presented with no
pain at all. She walked back and forth with no limp and jumped from
the floor to the table, no flinching. I watched the vet work her back
legs, no sign of pain. He says take her home and watcher her for the
weekend.

She slept all day when we got home, down on one of the lower beds,  in
a guest room, not in our usual room. Then she got up and had that
dreadful limp again. Jumped onto the high bed and cried and cried,
extending the rear left leg straight behind her.

Took her to urgent care at 6 pm. You guessed it, she did not present,
passed the exam with flying colors, no limp, no sign of pain. The
wonderful vet talked to me at length and said she had no idea what it
might be, but gave me prednisone in pill form because Cheeks is due
for a Depo shot for her asthma and linear granuloma problem and they
did not want to give the shot in case there might be a reason not to
have a steroid in her system for the months ahead. I insisted they
give me some pain medication so that I can give it to her if she shows
pain again. Back home now, she is limping slightly, warm nosed, but
otherwise her usual happy self.

I Googled this group for "limp" and related terms, saw that there was
someone back in February of this year who had a cat with the same
symptoms. It came to naught for him, and he assumed the cat pulled
something in a clumsy leap he had actually seen.

The only thing new in Cheeky's world is the cat window seat, which is
about chest level to me (I'm 5'6"). I have put things under it for her
to use as intermediary jump spots. Plus, the doctor said it is not too
far for a cat to jump.

Am I worried over nothing? I have the prednisone and complete
instructions on how to pill her over the course of the medication. The
vet said it is an anti-inflammatory and so might help any soft tissue
injury.

Thanks for all comments.