Hi Jid, alot of us are in the same situation. The differing opinions and contradictions are very frustrating and confusing.
I would never touch any chelation with amalgams in my teeth. The only thing I would do is tweak my diet and make sure all I eat is healthy and exclude the typical sugars, yeasts, glutens etc.
And of course supportive supplements, but never chelation until every scrap of amalgam is gone. It's enough that the mercury vapor comes off the teeth as it is, but if you are chelating at the sametime, you could increase the uptake into your body, so it might be defeating the purpose and will possibly cause more harm than good. (though again differeing opinions on this).
But then, it's up to you as it is all of us to decide what we wish to try and really, it's all pretty risky. The idea is to minimise the risks as much as possible, but they can't be eradicated. I've done things that have hurt me very badly along the way and wish i could change that. All I can do is try and pass onto others what could hurt them (if it hurt me), but because everybody is so different, what can be ok for some can really be opposite for someone else.
I know you're in a really difficult predicament. If you want to try this doctor's recommendation, you could, but really monitor your symptoms and stop immediately if you don't like where you're going. I've done many things, and I find you can try stuff, but never keep doing it if the symptoms start getting frightening.
100 mg of DMSA is not that high. If you want to ever try the every 4 hour protocol, you can just open the capsule, dump the powder out onto paper, flatten it out into a reasonably even shape (rectangle), slice it in half, take one half then and there as your dose and keep the other bit of powder wrapped up in foil or something for later, or you can put it back into the empty capsule. 50 mg is still a pretty high dose of DMSA for many just starting out, but Andy seems to think it's ok and reasonable enough for most. Though I'd recommend personally using 25 mg to start and go from there, either reduce later or increase depending on symptoms.
I belong to a mercury forum that is devoted to Andy Cutler's protocol and many are on there who are very well informed and have done many different protocols out there, some have been badly injured and will warn against any other protocol other than Andy's. Others are a bit divided on it and have had varying results. But all in all, they are all trying his protocol and you may get some helpful advice with anything you feel like asking them.
Here is the forum, just click on this link if you are interested -
http://health.groups.yahoo.com/group/frequent-dose-chelation/ 
