What you said about feeling better while using DMSA is interesting. I've heard about a number of people with heavy metal toxicity who feel better while chelating (then feel worse when they take a break). For others like me, it's the opposite (worse while chelating but better when I take a break).
I'm not sure why this is true. Just one of many mysteries surrounding heavy metal toxicity.
I think you are probably on the right track with the DMSA. It would likely take months of using it regularly and systematically (using the Cutler Protocol, for example) to feel really better. It took me six months of chelating to see serious improvement.