Talk to Pediatrician on Vomiting And No Appetite

AoA my 3yr old son (weight 17.5 kg) vomits alot. from past 4-5 days he has diminished appetite. everytime i make him eat something he immediately vomits . he also complains about stomach pain. dr suggested it as cold and prescribed syrup for vomiting, cold and stomach pain. but no medicine is seem to be effective. plus his colour also looks pale. his eating routine is half feeder bottle of milk before bed morning breakfast: paratha/egg , toast etc lunch time he takes a cup of pediasure and dinner includes roti/chawal and salan. he doesn't like any fruit. i tried many times but he refused to eat any fruit. i also try to avoid biscuits/chips etc. what should I do to increase his appetite and color from pale to reddish?