Mercury is one of he last metals to clear the body, after many of the other "lighter" metals have been flushed out. If you were very toxic, it may take longer than the average 30 day cleanse.
I was extremely mercury toxic (off the chart) and it took me closer to 90 days to eliminate most of my symptoms.
Often as the Amalgam levels are lowered, the Candida unbalance will resolve itself. Other times it is necessary to use a protocol. Two great products are, Threelac (Mona, who posts frequently on this forum, may be able to guide you as to where to purchase it) and Perfect Food from garden of Life.