I remember my "brain fog" came on suddenly like u described. Definately mercury related, possibly candida as well. I think its because finally our livers cannot put up with the toxic burden of the amount of mercury in our body and blood so higher levels are allowed to enter the brain. This is just a theory i came up with in relation to my own condition, as while the brain fog came on I was taking a drug called accutane which is used to clear up acne, but which very heavily affects the liver. Copper also mayb a problem for you like it was for me.

I know the feeling though, you feel detached from the world, things look different and you develop very scarey thought patterns, as well as the dizziness! Not good at all... I had panic attacks on top of that, which made everything so much harder. You will come out of the mental state you are in, believe me, with the removal of your fillings and the right chelation and detox process you will recover.