How do I get a useful, appropriate test for mercury?

Great news! My doctor takes me seriously when I say I suspect I have mercury toxicity. I wonder if it has to do with the fact that despite testing VERY healthy, perfect blood pressure, lots of other things going right, I am unable to lose weight no matter what I do.

Anyway, he says he's willing to do a test for mercury if I can find the information of how to do it, since I mentioned that the tests are rather specific (e.g. blood tests do not work since mercury doesn't stay in the bloodstream).

The thing is, I need to know a place in my area that does mercury testing. Like, what do they need to do - hair test, stool test, DMPS challenge? And what in my area would do it? I need to know for the Southwestern New Jersey area in particular.

I already know for sure of my condition, so this isn't for me; it's more like, if I can confirm that I have it with an official test, I might, for instance, be able to get the supplements that I need as a free prescription rather than buying them all the time. Things like that.

So any help would be very appreciated.