Hello. I have gone through your question and understand your concern. Children of this age group usually suffer from infected adenoids. The adenoids are lymph nodes located in the back of the throat behind nose, just like tonsil. As children grow older adenoids shrink and so does tonsils. However, they can swell up with infections and may lead to complications like ear infections, recurrent chest infections, sinusitis and vomiting. Treatment of adenoids vary from antibiotics to surgical removal of adenoids depending on the condition of child. In my opinion Otorhinolaryngologist [E.N.T] can be consulted to rule out adenoids as a cause of long standing cold associated with fever. Apart from treatment for underlying cause, regular intake of multivitamin and nutritious food along with good hygiene improves over all well being and good growth in children. Good luck. Hope your concern is answered. Thank you.