My opinion is that you should start with a parasite cleanse. Many here have had parasites. It is the result of a weakened immune system and candida overgrowth. A parasite cleanse formula should consist of at least these three herbs- Wormwood, black walnut green hull extract, and cloves. It should be taken for a month. You can get this at a vitamin store, or online from from humaworm.com

To help with the brain fog, plenty of vitamin c, b vitamins, magnesium and other minerals will help. To help with detoxification, you can take molybdenum 500 mcg, or 1,000 mcg a day. Molybdenum is needed to make the enzyme which breaks down aldehydes. Aldehydes are a waste product of candida yeast, which tend to overgrow in those who are mercury toxic. Eliminating sugar and going on a low carbohydrate diet. will help greatly.
The emphasis should be more on magnesium supplements rather than calcium, but some calcium should be taken if your diet is low in calcium.

To boost energy, you can take CoQ10 and carnitine supplements.
You could also take msm, and eat raw garlic(one clove(section) after each meal-chew it well)) which will help with detoxification.

Taking vitamin A supplements(10,000 IU a day) and zinc(30 mg a day) may help resolve your vision problems.

A very informative page.

http://www.flcv.com/cfsfm.html