I'm not sure if this will help, but here is a liquid B-12...

Liquid B-12 Complete

I would also add that I would use a test that measures T-3 with mercury toxic persons. Why? Because typical thyroid tests only deal with T-4 but T-3 levels are interfered with—and are usually low—in mercury toxic persons.

Also, B-12 supplements can help lower homocysteine. High homocysteine causes heart problem and high cholesterol. Is it possible that the current epidemic of high cholesterol is actually caused by mercury blocking the methylation of B-12? All evidence that I've read seems to indicate that this is the case. It may also be better for mercury toxic persons to use a pre-methylated form of B-12 to achieve better results.

Hope this helps.