How much milk are you feeding in 24hrs. If he is full child can not eat. Give milk only max thrice. . Since you are not sure. Keep record of temperature, food intake including biscuits, chips ext. Keep record of temperature. Stip all junk food .Give him idli. Dosa , rawa , banana, you can give even tomatoes after washing. .
Next Steps
Any doubt follow me. It require training. Of guiding parents and child.. give MV drops or syrups.