Actually you sound like you found the right dose--12mg. This is the dose that is most commonly acceptable in the early rounds according to reports from members in the Cutler groups.
In the Yahoo Cutler groups we are taught not to double the dose! We only increase by 50%. We also stay on a particular dose for at least a few rounds since sfx sometimes build up over a few rounds.
You sound like you need more magnesium and maybe vitamin c. these are two of the important supplements to take while on round--and off too--cf Cutler's books or the Files section of the frequent dose chelation yahoo group.
What supplements are you taking, how much and how frequently?
There are supplements you can take for those symptoms. Cutler has much on them in his Amalgam Illness book--noamalgam.com
Oral DMPS is usually better tolerated, esp if there is a history of nasty candida. I suggested it to a female friend for her early rounds since she has anxiety and is so sensitive. She is doing surprisingly well--as long as she does not forget her magnesium!
I used DMSA--16mg in the early rounds before adding a little ALA. I'm quite sensitive to ALA and the DMSA helps with the ALA sfx--fog, lethargy, etc. The sfx are manageable.
In the Cutler groups, if you get a reaction to taking a Hg chelator that is considered a strong indication that you actually do have an Hg problem. Your symptoms while on round with 12mg were the symptoms we see on round when Hg is involved.
STAY AWAY FROM EDTA when Hg is involved! It is rather well known to make Hg more toxic to the brain! It is an old chelator of lead but it really not necessary for most heavy metals since there are better ones now--DMSA, DMPS, ALA, and maybe some day, OSR.
Actually you have not even begun to get to the "hidden" mercury. You'll get to that with ALA. DMSA and DMPS mostly get to the HMs in the blood and extracellular space. However this is what you want to clear at this time. You don't want ALA finding Hg in the blood and carrying it *into* the brain as seen in at least one study with mice.
Remember some of us are not good at excreting HMs. You are likely one of them. There is thought to be a genetic component to this. Boyd Haley, former chair of the chem dept at the U of KY is an excellent source of info on this. http://www.myspace.com/video/vid/7383821
Therefore you sound like you are on track except you need to get better supported with supplements.
This is not a short process. Stick with low doses in the beginning as you tweak the supplement support and tweak your dosing schedule. After nearly 2 yrs I've been sticking with low doses so I'm functional while on round. I'm still only taking 10mg ALA + 20mg DMSA. I've had many, many gains. After being a sick and brain fogged for 15 yrs I am so grateful that I chose to chelate. It has changed my life and is changing the lives of those around me as they've witnessed my transformation!
I think you are wise to work with a doctor, even if he is a newbie at this too. Most doctors are. Mine was too. We were learning on the go but Cutler's information has been really quite accurate. I suppose the 15,000 members in the Yahoo chelation groups over the past 10 yrs have given him lots of experience. Of course that's on top of his own recovery from Hg.
I'm happy for you. It sounds like you are on the right track.