Yes you have to be such a detective with a lot of deduction and guesswork....if I get through this I might have a change of career and train to be a crime investigator ;)
In the Master's book he does mention a precoproporphrin (is that even pronounceable??) test which is a specific marker for mercury intoxication. Basically it's just more sophisticated form of the porphyrin test. He says only a few labs do it eg Metametrix....US lab presumably....so maybe you could have that done.
I think zinc and copper can both be normal...but I suppose it's all about ratios.
Good luck with the lyme, hope you get through it :) Are you going to try the salt/vit C?
The merc forums probably argue more as they've probably all got mercury induced borderline personality disorder ;)