Oh my gosh, what fabulous posts!! I'm so glad that your girl is improving in different ways. Who knows what it is but don't stop!! LOL How great to see that grinning smiley you posted.

In response to the post about your vet not finding this regarding Puddy's tongue, I just wanted to add that nowhere on the internet could I find this tongue/burning mouth syndrome in connection with cats, just people. But it does seem likely that if it is a symptom for people, it could certainly be one for cats too. And because so many of her other symptoms line up with a B deficiency, it makes sense. What I'm wondering though is why the levels of Vitamin B wouldn't show up on bloodwork if they were low. But in any case, from what I've read, it's safe to give and if the body doesn't need it, it can get rid of it. There is an issue with what is water soluable and what isn't and one site said that B12 is and another said it wasn't but your vet should be able to give you a clear answer.

It is so funny how little things can be so exciting but I too was cheering away in my den when I read about the drinking and the litterbox use and lack of howling. It is all such good news. And if I've been able to help, I'm so happy because you guys helped me a millions times more with Tiger and Jimmy etc.. That is the wonderful thing about PT. A place where we can share stuff and bounce ideas of each other and think about each other's pets during our day to day activities. It is neat and I don't know what I would have done without it for the past year, it helped so much.

p.s. I found some more stuff supporting the concept that what is first thought to be dementia may be a vitamin B deficiency instead. This again is from a site with regard to people but I think it's really interesting.

CHRONIC VITAMIN B DEFICIENCY

Vitamin B deficiency can sneak up on you, because it doesn’t have to create serious health problems right away. In fact, medical researchers have discovered that very often there can be no detectable signs according to scientific instrumentation, that you are experiencing a deficiency. For example, “memory impairment due to vitamin B12 deficiency can precede blood symptoms of deficiency by years. Evidence that vitamin B12 deficiency accounts for some cognition deficits in older people comes from a study that revealed abnormal short-term memory in more than two-thirds of clients with pernicious anemia…The researchers recommend that a diagnosis of senile dementia should not be made, even in the absence of anemia, until vitamin B12 status is determined biochemically.” (Hamilton, p. 476) This means that it is possible that certain mental disorders can be directly attributable to vitamin B complex deficiency, and it is easier to first start replenishing stores of vitamin B complex than to begin treating difficult mental illnesses with drugs, therapy or psychological counseling.
Since Puddy has anemia and was acting a bit demented (that sounds so mean-lol) it hopefully could mean that it may not be dementia but a side effect instead. I'm praying that this is the case.
And the highlighted 'blue' part answers my question about the blood work I guess.

Eat more vitamin B-containing foods — oats, barley, wheat bran, avocado, salmon, Brazil nuts and others.
I guess Salmon is the only thing in that list that would be appealing to a cat. I can't remember if it is one of your cats or one of Candace's that doesn't like salmon.

It took a while to create a vitamin B deficiency, so it takes a while to reverse the problem; with severe cases it can take a year or so, with milder cases it can take just a few days.
The above quotes came from this site.