Thanks for your query
i can feel your concerns
if he is pale with frequent pain and gastointestinal upsets then coeliac
could be a possibility. u can rule out by doing certain tests and biopsy
after consulting your doctor.
is he having diarrohea ?
i advise you to check his haemoglobin
level and if found low,then give him iron suppements after consulting your doctor
improve his diet.add meat,fresh green leafy vegetables and fruit to his diet
wishing him good health