Hi Doc, my son is 4 years old, and very frequently he is falling sick,and he is also going to school . most of the time he suffers from cough and cold.. even he has.vomitings sensation frequently.docs saying its a seasonal one .but thing is he is not recovering fast from his sickness and again falling sick if exposed to any climate changes. please suggest me how can I improve his immunity . he is also picky eater.