You need a trial of two weeks with an anti allergic, an anti leukotriene, a steroid nasal spray, a mucolytic and steam inhalation. Many a times the infection is fungal, hence antibiotics do not give relief. Intrinsic or vasomotor rhinitis will also respond to such treatment. If you do not improve with the above medication, look for physical obstruction in the nasal airflow by undergoing a plain CT PNS (Para Nasal Sinuses) on a multislice CT Scanner and rhinomanometry . You should also rule out GERD (Gastro Esophageal reflux Disease), cardiac and chest causes. Discuss all this with your local physician.