Help! 5yo w/ very low potassium & getting worse!

Please help! My mom has raised this cat from a kitten and she never leaves her side, and the vets don't seem to have a clue!

5 year old Siamese with no health problems except chronically "gunky" tear ducts, and a previously abscessed anal gland which has not been a problem lately.

She now has potassium so low that she's weak, unsteady and can barely walk, unable to lift her head so her chin is tucked up oddly, and not eating or drinking so she's already dropped to 6 lbs IIRC.  They vet did a full bloodwork panel and the WBC count (white blood cells) was slightly elevated.  There are no other apparent symptoms.

Yesterday the vet injected an antibiotic and steroid and is giving a potassium supplement.  Today they say she's weaker and they're increasing the potassium supplement.  They say they basically don't know what it is, and they're not even trying anything new!

Any suggestions are welcome. Thanks for your help!

(P.S. It's a good thing that possibly the most important forum, "Ask a vet", has a total limit of about 3 questions per day. Way to go.)

[FieroGT42]

The vet has been spending every spare minute looking through various resources to no avail.  Blood work is not indicative of renal problems, diabetes, etc.  Potassium supplement was increased, but she's still doing worse.. so weak now that she's nearly "paralyzed".  I'll keep doing research in the meantime...

[Savas]

The problem is kitty is suffering from Something that's affecting her kidneys. The question is, what is it?

Assuming that he's run the standard tests, I'm not sure what to suggest. Anything i'd do would be guesswork (like environmental poisoning...heavy metals can cause kidney issues leading to low pot. levels. Or something complicated like a tiny bowel perforation causing toxins to leak into the blood stream causing the same result). You see what I'm getting at. Is this a regular vet or a fully equipped animal hospital? In terms of diagnosis, it makes a huge difference.