Thank you for your query on Healthcare Magic.
and paleness is due to presence of anemia and the presence of sores or tongue, mouth which are recurrent is due to vitamin deficiencies especially B group vitamins.
He requires multivitamin
Once get his hemoglobin
level checked and if it is low an iron syrup can be started to treat the anemia.
Give balanced and nutritious diet which contains vegetables, green leafy vegetables, fruits, liver, and meat, and eggs.
Consult your Pediatrician
for the examination and prescription of medication.
Hope I have answered your query.