Hi, the most common cause for nasal obstruction is Deviated nasal
septum (DNS). This condition leads to obstruction and breathing difficulty. This can lead to
sinus infection, ear infection and headaches.
Other possibilities are laryngeal web, asthma, any structural abnormalities in the nasal passage such as nasal polyps, hypertrophied turbinates etc.
You need to undergo detailed examination of nose and radiography of the sinuses to rule out existing sinusitis.