Hello Welcome in H.C.M. I have gone through your query regarding frequent cough since birth, Initially your son was diagnosed as allergic rhinitis at the age of 2 months, but now at the age of 6 years he is having same problem and diagnosed as deviated nasal septum. Deviated nasal septum is a primarily clinical diagnosis because deviation may be in both cartilagenous and bony part ,some times it is in cartilagenous part only. When it is in cartilagenous part only the X-ray and even C.T. scan will not show it. Most of the times deviated nasal septum may give rise to other complications like sinusitis, polyposis etc which are responsible for continuous nasal infections. To diagnose and treat it following basic investigations are necessary- (1) C.T.scan of paranasal sinuses. (2) culture and sensitivity of nasal discharge. (3) X-ray chest - P.A. view. thorough examination of chest to rule out any sign of spasm along with nasal examination and co relation of inferences of investigations with clinical findings will tell about diagnosis and possible treatment. With regards.