The only way to know for certain is to get tested for heavy metals; I believe they can do hair tests, etc.
The way my naturopath looks at things is that there is your fire and your water. Your fire is you long term energy/strength reserve and your water is your short term energy reserve. If you support your water, then it will occasionally splash back into your fire and strengthen this reservoir.
You’ve(or candida) beat yourself so down over the years that it takes a lot of rest and proper treatment to replenish.