K.,
A gluten free diet it not going to help an individual who is allergic to yeast.
Individuals with a yeast allergy will also cross react to mold so that also needs to be eliminated from the diet, so you need to consume all products within 3 days of opening them or keep them frozen until you are ready to consume it.
Mold can be found in cheese and fresh milk. It is best to consume either frozen or canned fruits and veggies. Anything that has mold that can be seen on it should NOT be eaten as the mold is throughout the product. So if you decide to consume a tomato and it has a small piece of mold on it, your child will react.
You will need to read food labels, because alot of products contain yeast that you would not thing did, ie. doritos.
Here is a website for the yeast free diet, but I do NOT agree with including any cheese in a yeast/mold free diet. Most cheese is made with mold and mold is a natural contaminate of it as well. So cheese should be eliminated entirely. I recommend soy or rice cheese to replace regular cheese. They are not made with mold. I keep it frozen to prevent contamination though. This website is concentrating on eliminating
http://www.theyeastdiet.com/yeast-free-diet.html
Others have recommended some really great resources.
T. Cornelius, MS, RD, LDN, CLT
For more information go to
http://nutrition.bitwine.com/advisors/tcorneli