I find hair tests rather worthless because metals will only show up in your hair if your body is excreting them. Most of the sickest people are "non-excreters" and do not remove heavy metals at a normal rate.
My wife had a hair test that showed nothing while she actually had high blood mercury; her challenge test showed massive amounts of mercury as well.
Do you have any lead exposure? Lead-glazed bathtub? lead paint? Well water? etc.