Respecting & Working with Challenging Behaviors vs. Caused by Food Allergies?

I have been working on living respectfully with my children. For me that means accepting them just as they are - the "good" and the "bad" (who decides what falls under those labels anyway?) - and finding win/win situations in everything we do. Things are going GREAT, but I am struggling to understand which parts of my previous "knowledge" about autism and the possible causes of autistic behaviors are still useful and ring true in my new life.

I KNOW that all behavior is a form of communication, but what are they trying to communicate?

When Jason spends all day yelling at me, insulting his brother and even hitting anyone in his path is he simply frustrated by something going on or did he eat something that is making him feel bad inside? I know that if I don't feel healthy, I don't always act my best. So ... in true unschooling style ... should I work with Jason to develop communication strategies, empathize with what I think are his frustrations, try to redirect him, etc ... or should I go ahead and get him tested for food allergies or food sensitivities? I know that it is always helpful to learn new strategies for living cooperatively and peacefully, but I wonder if I am simply putting a bandaid on a gaping wound. I worry that I may be overlooking the root cause of the behavior (food allergies?) by completely focusing on the behavior itself.

Let me include some info on the correlation between behavior and food allergies/intolerances.

The IgG antibody mediated response, also known as sensitivities, delayed or hidden allergies can cause many things. I have bolded and underlined the “autistic symptoms”. These allergies produce symptoms such as red burning ears, low grade fevers, itching, runny or stuffy nose, joint or muscle aches and pains, headaches, diarrhea, constipation, excessive gas, irritability, mood swings, confusion, mental fog, aggression, faintness, dizziness, bags or dark circles under the eyes, ringing in ears, insomnia, heart palpitations, chest pains, coughing, hoarseness, acne, hair loss, hot flashes, heartburn, craving certain foods, water retention, weight gain, weight loss, hyperactivity, poor memory, poor comprehension, lack of concentration, fatigue, stuttering, slurred speech, anxiety, depression, itching, frequent urination and many others.

( from http://mothers-reversing-autism.com/autism-food-allergy.html)

So, at this point, I have decided that I have to get both boys tested for Celiac Disease (problems digesting gluten). Depending on what I find out from that test, I will either go further in their medical testing, adapt their diet myself, or ... I don't know. I just know that I have to take that first step for their health and my own knowledge. While waiting for the tests and their results to come, I will continue working on being VERY present with my kiddos and working on those wonderful communication strategies.