Mel,

No need to worry about overdosing on the B-12. You could ingest handfuls of the stuff and would be fine. Most sources list no known levels of toxicity. It is water soluble - your body will use what it needs and the rest will be excreted as waste in urine.

Not sure if you were asking again about the thiamine and ALA - I gave one opinion, there may be others, but I am suggesting that it would be useful to hold off on other supplements for a bit to see what effect, if any, of the B-12.

rafi