Extra virgin coconut oil is a strong yeast killer. That's what's likely causing your die off symptoms. Even if you spit it out after pulling, some of it will inevitably find it's way down your throat and into your body while you're swishing it around in your mouth.
I'm currently retrying cilantro/chlorella as a chelator. You might consider trying it too. I think DMSA/ALA would be slower and likely safer, but cilantro helped me feel better 6 months after I began using it the first time. The side effects can be unpleasant though. I can definitely feel it working more than the DMSA/ALA did (more phantom mosquito bites, for example) now that I'm using it again.