You should stop all sugar. Especially eliminate juice! My son had candida bad (intenstinal), we used homeopathic drops from naturalpath dr. Make sure he gets a high protien diet, as yeast feeds on sugar and carbs but cannot do anything with protien. Limit fruit to only 2 pieces or less until it clears up. Include probiotics acidophilus bifidus etc, just make sure it is for kids!
Also you may want to make a tea of Pau d'arco for him. As far as topically you could make a oil solution with a few tbsp of olive oil to 10-15 drops of tea tree oil (until you can smell it. Maybe even add lavender which is also antifungal (however anti-bacterial so careful) Good Luck!