Sorry to hear that you are struggling with this. Some members of the Yahoo detox groups report this as well. I have no history of "saddness" Depression but experienced some of it during the worst of the "stall" phase, around 7 months after Amalgam removal.
Some things to consider:
Yes, Bs (several x per day)
Magnesium several x/day--don't skimp and consider using a fairly well absorbed form or combo of forms--citrate, glycinate, sulfate not cheap oxide.
Maybe certain amino acids.
Maybe thyroid support or medication. Do you have a history of low norm T3?
I think Andy writes that a need for more adrenal support can be involved.
Unfortunately there might not just be one factor when HMs are involved. HMs affect various systems in the body.