Hi Catherine,
Please do your research on the chelation therapy before moving forward. At one point we went to a "functional medicine" doctor to get a more comprehensive view of hormonal and vitamin levels. He too wanted to do chelation but it was the IV method. At this time, John was on Exjade and still dealing with high FE so we were not planning on doing chelation. After researching it and talking to some his patients, there's always a segment of people who end up feeling worse from the chelation, especially the DMSA. DMSA can create new issues for you like food allergies to any food with sulphur like garlic and onions. Especially if your health is already compromised, chelation will can be harder on you. Just like with treatments for AA/MDS, no one can predict what your reaction will be. Oral is probably safer. Here's a site on adverse effects of DMPS, which is another sulphur based chelator.
http://www.dmpsbackfire.com/dmsa/default.shtml
Chelation releases a lot of heavy metals which is very taxing on the detox organs. If your body cannot handle that, the toxins will take up residence else where in the body. Unfortunately, they cannot identify the organs that are compromised by the heavy metals and target the chelation to them. IMO, detoxing a small amount in the compromised organs/tissues would be so much more powerful than a shotgun approach.
I personally feel that less is more. There are less aggressive ways to detox.
Getting the liver glutathione levels up will go along way in improving your body's detox capability.
Which leads me to glutathione. Glutathione supplementation is not very effective in increasing tissue levels of glutathione. There are other nutrients, like NAC, Lipoic Acid, milk thistle, that will improve your body's production of glutathione. And vitamin C is critical.
On the B12....Bruce may not be converting the type of B12 he's injection into a useable form. The methyl form of B12 is bio-available, the Cyno form is not.
I don't mean to discourage you regarding chelation. Many have been helped by it. Just put a critical eye on it.
BTW...after spending lots of $$$$ on tests, we walked away and self treated. This guy was just too aggressive and cavalier for our taste.