I would advice to postpone any diet or treatment until after your championship thing.
To answer your question: The whey protein is lactose and feeds your candida. This gives an energy boost. Anything that feeds candida in the very early stage will give you an energy boost.
Switching to too strict a diet will mess you up I fear. Candida comes from internal weakness, in your case, it seems, the antibiotics. Your condition presumably being not so bad, I would advice to keep busy with being an athlete, while concentrating on that internal weakness. You need to focus on rebuilding your gut flora and with that inner strenght. So instead of starving yourself and nuking your body with antifungals, concentrate on the cause and work towards health with probiotics, exercise, and good food.
Also, I have to ask: do you suffer from stress or anxiety of any kind?