This is Allergy, a component of Allergic Rhinopharyngitis. You will have to use a steroid nasal spray like the 1 containing Fluticasone spray 2 spray 2 times a day for a couple of months along with a combination of an anti-allergic with Monteleukast every night for a week or so.
Next Steps
If it doesn't respond, start Cap Azithromycin 500 mg daily for min 3 to max 5 days.
Health Tips
Do warm saline gargles 3 - 4 times a day.