My wife is a celiac who also battles a systemic yeast (A.K.A. Candida) problem. We watch her blood sugar regularly and use a natural sweetener called, Agave Nectar, to make our favorite low GI desert(s). She also eats protein with every meal which helps stabilize blood sugar so that it does not spike, which the yeast loves. Probiotics are big and we did find two nutrition bars that didn't seem to cause her any problems. The more popular of the two is Larabars and the other is Allerenergy (not considered low GI).
Generally speaking it is not advised to use any sweeteners until you have the yeast in check. My wife's doctor is a Naturopathic Doctor and is wonderful with this type of problem. As a ray of hope, my wife cannot have gluten, wheat, soy, sugar, yeast, casein and lactose. It has been a very long, up hill battle but we have found balance.
Best of luck, I understand how difficult this can be.
jjjhawk88