Hi thanks for contacting HCM.... You have done all possible work up like USG, blood test and even endoscopy and CT scan also .... So no chance of organic causes .... Here it seems most likely functional bowel problem .... So try to instruct your child to avoid outside food .... Give him healthy balanced diet like green leafy vegetable , fruits etc more .... Excess tea , coffe , smoking avoided .... Non veg food very less ..... Avoid stress as it can aggravate gastric problem .... Rule out parasites infection by stool examination ... When gastric pain and spasm buscopan and omeprazole can be given. .. Consult physician ... Take care ...