You are right about hair analysis in general. If done correctly it is more informative than other tests which are readily available.
You doc seems to be a nice trustworthy guy, but not very knowledgeable.
DMSA must be taken every 4 to 5 hours, or it will REDISTRIBUTE heavy metals into your CNS and your brain. Taken on a proper chelation schedule, which is NO LATER THAN every 4 to 5 hours day AND night like clockwork, it is VERY SAFE at proper doses. Yours is probably far too high to start with, but since you aren't feeling anything it makes me wonder if the diagnosis is correct. I'd suggest you get hold of Andrew H. Cutler's, PhD PE, book on hair analysis, and do the diagnosis youself. It's not rocket science. You can get the book directly from the author (or from Amazon; author's website offers a better price): http://www.noamalgam.com/booksforsale.html
Forget about IV chelation. It can be lethal. If it's not lethal and you are toxic, it can do so much damage to your brain that you will be committed; happened to many people. Forget about IV chelation real quick.
Other than that, if you want to stay sane and get well, I'd suggest you read the excerpts of "Amalgam Illness - Diagnosis and Treatment" available on http://noamalgam.com/
The book is worth its price in gold.
Also, your deal on DMSA sounds like quite a ripoff. Check out VRP.com.
PS: I'm not affiliated with the author.
I simply think Andrew H. Cutler, PhD PE, is brilliant and he knows what he's doing, unlike most anyone else in what is becoming a chelation/detox industry.