Candida is nothing more than one's body not having enough zinc and vitamin d (and possibly other co-factors) for optimal immune function. When the immune system can't keep in check various mircro-organisms, one or more will overgrow leading to candida or c diff infection or numerous other problems.
Some things to cosider:
How much zinc are you getting?
How much D from supplements and sun?
What is your 25(OH)D level?
Are you getting midday sun? How often?
How much Mg and K (potassium) are you getting from food and supplements?
How much exercise are you getting? Lifting heavy things?
(ah never mind, just saw your answer there....this is huge for brain function. See Daniel Amen's books and John Ratey's book)