Mercury could be a factor so if you have Amalgams consider replacing them
Iodine(lugol's or SSKI ) may well help, Take a look at the Iodine forum
MMS may do something but Iodine is the first thing to try,
because it can help with mercury and also halogen imbalance which Miracle-Mineral-Supplement cannot,
Fluoride could also be a factor if you are exposed to it through water.
Best to consider chemical causes and halogen imbalance before psychological methods