Methamphetamine, ouch, probably a mixed drug picture. What a wonderful job you do!
How much selenium. I would estimate 100 mcg per week, maybe more if you up the iodine.
Magnesium, 50-100 mg per day (also give some vit B for the uptake of magnesium and zinc)but start slowly with the magnesium, it may cause loose bowels.
Boron; 3 mg every second day if just for general health.
If to adress a fungus issue, I am afraid more is needed, and in the form of borax. If in US; mountainroseherb has a good one that I gave to kids, cats, plants etc:)
Just a pinch needed, dissolved in a teaspoon of hot water, then fill a glass with juice, (add vit C, Iodine if you like) This will give approx 2 mg of boron.
If the fungus is topical, borax is great as a wash. I mix borax, warm water, Iodine and a few drops of essential oil (lavender is great for the small ones) Let it sit for half an hour before rinsing.