your son needs an immediate consultation with a surgeon and a clinical check up . clinical check up and investigations as required to be done for proper diagnosis and right treatment . most probably
your boy is suffering from severe gastritis
with oesophagial reflux ,gerd[gastro oesophagial reflux disorder. clinical examination with detailed history will decide the type of investigations to be done .
worm infestations may be the cause of such complains. stool examination ,a barium meal
study for upper g i , usg of whole abdomen will be helpful .
please get your boy checked and investigations done for proper treatment .