Nancy,
If you are thinking there is a possibility of celiac, that could be the
cause of the diarrhea.  Looking at his diet from a celiac point of view,
there are many possible causes of diarrhea, i.e., Kix, Froot Loops, pasta,
graham crackers. chicken nuggets and crumb cake. How long has he been off
milk?  I have heard that for some odd reason that when you go off gluten
(for celiac) the symptoms of dairy problems are magnified.  Maybe this is
the reverse?  I don't really know, I am just throwing out a possibility.

Kathy