Hi Doctors, My son , 6 years old , is a G6PD deficiency boy and is underweight, weighing less than 20 kg. Each visit to the doctor will always get the same comment - underweight. Have tried multivitamins but he will always fall sick with cough and fever. As he has Sinus problem also, the minute he comes down with flu and cough, it will take at least 1 month to recover. His appetite is fine and he eats regular meals at regular times. May I know how can I help him to gain more weight and be more healthy ? Thank you