Yes, to all 3 questions.

First off, tried a 2 different brands of methylcobalamin. The one mixed simply with water, pure cobalt stopped my breathing. Because of that, I was sent to an allergist who, after testing, determined i indee had a metal allergy. Of note: as an artist, I spent the first 20 yrs of my life licking the paintbrushes, as was instructed by our teacher. It gave a perfect point to the brush. ekkkk. Well, not good, as we used cobalt blue for everything. Okay, I already knew I was allergic to metals, gold, silver, etc...No doc would believe I could be allergic to cobalt, though.

It was never recommended to me to try the hydroxy or adeno-whatever...I will react to anything given to me. My team of docs are trying to keep my system from doing anymore changes. For example: I've recently been put on a topical magnesium. I can't sleep when I use it, flat out. I use it for muscle spasms. The muscle spasms (I have snapped an ankle tendon twice due to them) come when I use my narrow band uvb lamp for psoriasis. The vit d I get from the therapy lamp, quite a bit, sends my potassium/calcium into fits. go figure...

My neurologist told me that b12's job was to keep the myelin around our nerves in good repair. Think electrical wire that's been worn. It malfunctions. With my lifetime of inadequate b12, my myelin was shot. Add b12 and it began to rebuild..puff up, as I was told. Too little b12, even now, results in pain. Due to my adverse reactions I was told to not take it for 2 weeks..did that..back to level 10 pain by day 2. I then restarted on the very small doseage with less impressive results but still, better than horrible pain. Another thing that b12 does is to relax our muscles, tendons...that also helps with any pain.

I use the subligual because of several small bowel resections. I can't tollerate any pills or capsules, and the methyl-b sublingual supposedly is absorbed by the nerves directly under the tongue, heads to the spinal c3-4. I believe this is the area where b12 is then directed to it's various chores. It's the key that opens our cells ability to respond to the specific functions required.

Also had my lungs, heart, and sinuses checked out, as well as testing for possible ulcer and gerd. All major body parts are working fine.

I don't understand why there aren't others who react as differently as you and I do, but perhaps these others simply give it a try and then simply quit taking it. I certainly can't be the only one with oddball autoimmune diseases that needs b12.

deb..