Sometimes a reaction that feels bad is a good thing.
It's common to have side effects with any chelator. The chelator pulls the heavy metals from where it's gotten stuck in your body. Usually, by the second day of chelating, there's enough of the heavy metal in your system for your body to think it's been poisoned, and it reacts to it. This makes a person feel bad.
Some people react more than other people. It all depends on your body and how much of the heavy metals you have in your system. Yeast plays a role in the reaction as well. Reducing yeast can reduce problems during chelating.
Over time the reaction becomes less and less because there's less and less heavy metal to be released. I had fairly bad reactions when I started. Now I have almost no reaction at all.
You will have less of a reaction if you drink a lot of water. Saunas (or just making yourself sweat and then showering) will help too.
The DMSA will be more effective if you use it every 4 hours (including overnight) on the Cutler Protocol. This should be done for 3-5 days plus a 3-5 day break to let your body recover. It will take the metals out of your system if used properly.
Cilantro (coriander) is an example of one that does not carry the heavy metal out. It pulls the stuff out of its hiding places and lets it loose in your system. It should be combined with chlorella to help carry the metals out of your system. This method is known for having some pretty bad side effects, and many people don't recommend it.