You generally get thrush when your immune system is worn down. It can get warn down from excessive over training which of course can be due to poor diet, lack of sleep, too much stress, or using bathtub brew or a combination of all of them. Chances are you also have digestion issues and a buildup of candida in your intestinal tract as well. Lot of drugs like antibiotics and corticosteroids can wreak havoc on good intestinal bacteria. CUt out simple carbs so the candida has less food and get on some good high potency probiotics.