G.B.
Magnesium supplements , and, rubbing magnesium oil on his skin, will help to keep a fungal issue clear. Also keeping milk products way down will help- because milk depletes your magnesium.
Xylitol is a type of birch tree sugar that tastes good, but when you eat it the bacteria/fugus eat it and cant digest it and it kills them. So it will help both fungal and bacterial problems. It also keeps blood sugar lower (if used instead of sugar) which helps keep fungal issues at bay.