well v that sounds pretty crappy.
b12 deficiency and ms are 'supposed' to be two distinct conditions. as in, you don't diagnose ms if there's b12 deficiency in the picture. ms certainly should not CAUSE b12 deficiency. the two definitely have similar characteristics though, right down to the pattern of lesions in the spinal cord.
if the bf has no obvious lifestyle reasons why his b12 is down, i would think the docs ought to have been looking for other reasons for sure.
have you ever heard mention of a:
homocysteine test http://www.labtestsonline.org/understan ... lance.html
methylmalonic acid (MMA) test http://www.labtestsonline.org/understan ... /test.html
parietal cell antibody test?
also FYI the normal range for b12 is a bit off. there should be some posting along those lines on here somewhere, from early 2006 when i first joined. even if they said he was normal range, that could be down around 220 pmol/L. if someone has ms, better to keep it up over 500pmol/L if possible.
so all in all, you may be interested in finding out which tests have been done and if they do have a 'why' of sorts, knowing why tells you how to deal with it, and when you do followup testing to check on his b12 status, keep in mind that 'it's normal' is not a good enough answer when you're sick! you want to know the number, the units, and decide for yourself.
finally, if his b12 level has been deficient for a long time, he has probably drained a bunch of things that usually need b12 in order for the body to process them properly.
depending what is going on, vitamin E might help him get some b12 to stick, and adding the rest of the b-complex could be useful also. sounds like you really need some answers though before you can figure out how to take it on.