I would like to be more enlightened. Sue Gilbert Sue is a consulting nutritionist. For many years she worked with Earth's Best Organic Baby Food, integrating nutrition and product development. She has written numerous articles on children's health and nutrition for parenting publications. You are absolutely right to be getting in touch with your child's pediatrician.
Medical problems deserve medical answers and solutions.
There is no doubt that good nutrition is important for optimal health, but it is not the solution to medical conditions, with the exception of those problems created by poor nutrition, e.g. rickets caused by lack or vitamin D or anemia caused by too little iron. Good nutrition can help to boost your immune system to help you resist and fight off illnesses. Some foods are known for their immune boosting properties. Yogurt is one of them. The description of your son's diet does concern me somewhat.