[crystalp]

The test for gluten sensitivity (Celiac Disease) can be done two ways.
First, the doctor can order a blood test. If you do this one then E needs to be on a regular diet including gluten for it to be accurate.
The second way is to cut all gluten from his diet. A lot of times, dairy and oats need to be cut out at first, also, because the part of the intestine that is damaged by Celiac is also the part that helps to digest dairy. So until the villi "grow back", dairy is really hard to digest and can cause symptoms. Oats need to be avoided at first because in this country many oats are cross-contaminated with wheat because of how it is grown. If he gets better on the diet, then you can be pretty sure that he has a gluten sensitivity or Celiac Disease. But you would want to get it confirmed by a doctor.