Kitty recovered, now the other kitty has symptoms
New to the forum but was seeking a solution for the exact same symptoms.
Took my baby girl kitty to the emergency (xrays, bloodwork, nothing found) then to a cat specialist (extra extra bloodwork, nothing found). Specialists suggested a neuromuscular specialist or accupuncture and prescribed light steroids. I switched food, held off on the steroids hoping she'd "snap out of it".
I switched to envelope soft food instead of canned. Stuck with chicken only.
And - in a week or two, she gradually started being her frisky, jumping self! This lead me to believe the problem was ingestion or exposure related. Though, I'm still uncertain.
Now...the boy kitty has slightly weakened back legs!
I will attend to the kitty litter - that one is news to me and worth a shot.
Also - I found I have poison house plants. Philodendron and Croton and Aloe Vera. All lovely but toxic - so I'll be passing those along to friends/family. (I grew up with outdoor farm cats so the whole indoor kitty care is an entirely new learning experience).
It is distressing. I'm open to learning as much as possible to get this resolved. I hate not being able to help or fix it. So please keep posting as you try and learn anything related!