Hello Bex. The link I gave in this thread emphasizes that the main feature of MSM is its detoxification capabilities. Perhaps you felt worse while taking MSM since your body was detoxifying? As far as feeling worse at certain times, I can't pinpoint the cause. It could be detoxification of toxins other than mercury, candida die off, parasite die off, or perhaps mercury being pulled out of organs and getting into the blood before being excreted. None of these are bad things, but they may make you feel worse in the short term. I say give msm a chance. If someone gets intolerable symptoms from it then they should stop using it immediately, however if their symptoms just get a bit worse then they may be healing because of it and should continue taking it. My view is that msm should be taken unless there is a very good reason not to take it.