Holy cow are you me? I haven't had as bad an experience as you either in terms of symptoms or medical care, but I'm hoping that right now I'm turning a corner, having started supplements of both of these and am feeling a lot better.

The weirdest things I've been through were uncontrollable muscle spasms and numbness on half of my body, in various places. I had shingles a little while back and it seems like that side was affected more by the nerve issues. I've had a lot of anxiety about strokes, but I'm finally starting to chill out about it. I've only lost 10 pounds from the digestive issues, luckily, though I was already on the thin side.

My D is already tested as mildly deficient, and B12 I'm getting myself tested next week (the most sensitive tests you can get, Homocysteine and Methylmalonic acid). But the drastic improvement I've felt while increasing my B12 intake has been pretty telling. I think it's helped a lot more than the D supplementation, which gave me a bit more energy but didn't do much for the really bad symptoms.

I'm vegan and was actually supplementing B12, about 250 mcg per day. I thought that was enough, but my current theory is that I've just been getting barely adequate intake given that my digestion isn't always great, and the recent bout of shingles I had combined with some anxiety about unrelated life stuff pushed me over the edge. Then I tried taking a bunch of B12 one day just in case that was the issue, and felt absolutely awful -- which I unfortunately interpreted as "B12 caused a bacterial overgrowth in my intestines" and not "My nerves are damaged and started to repair themselves, and my brain is getting temporarily over-stimulated with sensation". I think the latter was what actually happened, but because I believed the former at the time, I stopped my B12 for a bit and that did not help. I thought I had enough stored in my body that skipping a while, then resuming a reduced dose, would be fine.

For about a week now, I'm taking 1500 mcg per day split into 3 doses, which is supposed to let you absorb a lot more than a single dose (though still only a tiny fraction of what you take, maybe 6-12mcg instead of 2-4, as a wild ballpark). The biology behind B12's dose-absorption curve in pretty interesting. Your stomach lining produces a chemical called "intrinsic factor" which B12 has to bind to to be absorbed, because it's a big chunky molecule that has a really time passing through your intestinal wall alone. Once that intrinsic factor is all used up, you have to wait a while for more to be produced. But if you take a TON of B12, some of it does manage to get through by chance, even if not bound to the intrinsic factor.

Funniest/scariest thing that happened to me was just a few days ago, when my jaw started opening like a yawn, repeatedly, and uncontrollably. I could only get out a word or two before my mouth would open. The morning after getting checked out to rule out stroke (hooray, another ER visit), I realized that I had started yawning again after not really being able to yawn for a long time, and not even noticing it as a thing that might be related to everything else. I think that was the nerve that controls yawning waking up and getting a bit over-excited. It eventually passed after about an hour.

As bad as this has been for me, I've been very lucky to already have been interested in nutrition and had enough background knowledge to figure things out after only a couple of months and without my symptoms getting too bad. (assuming I'm right, that is -- I'm reasonably confident but I'm trying not to get my hopes up too much).

I can't imagine what it would have been like to go through what you went through. I'm glad you eventually figured it out.

I think a big problem with B12 deficiency is that the symptoms are varied and often vague enough that all sorts of folks who don't know what they're doing have latched on to it, and people often self diagnose with it incorrectly, possibly delaying a correct diagnosis. I wonder if some doctors have just seen too many people who do this (but maybe I'm being too charitable). Yet it is a real and deadly serious issue, and the standard guidance on it is maybe a bit out of date.