Juice and Fruit

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.

If it has really cleared up and been clear a while, moderate amounts of fruit are probably fine, especially if you make sure he's eating something with acidophilus in it the same day. Juice has the problem that many are sweetened and it lacks the fruit fiber to keep the massive sugar shock from happening in the system. You can make sure the juice he drinks has no additional sugar added, and dilute it a bunch, and it's not as much of a problem in moderation. But it's still a good idea to take adding sweet things very slow to make sure you don't get another yeast bloom, and to make sure he's getting lots of fiber and acidophilus any time you're serving sweets for a bit.

of course! Yeast infections are bad bacteria in the body, so start him on an acidophilus supplement. Its a probiotic, so it replaces the bad bacteria with good. This will prevent yeast infections.

Do a little at a time- it could be only some fruits. My sis had the same issue with fruit. Her daughter was horrible. Just do a little at a time and with other foods. Not a bunch for lunch etc.
Good luck! Fruit is so yummy!
Maybe try fruitables juice with fruit and vegetables in it!