Praying for your child.

Sometimes stuff like that is digestive problems that can be fixed easily by adding digestive enzymes and/or Betaine HCl.  I take both with every meal.  Both are cheap and non-toxic, so can't hurt.  Digestive enzymes can be found in chewables, but I think the Betaine HCl is only available as a capsule which might not work for a 6 year old.