Adding a tiny little bit salt into warm water, use the salted water to clean(a cleaning way in Yoga. The water comes in from one side of the nose while your one finger is blocking the another side. It looks like using your side nose to drink water and hold it. Then keep your head up and way back until the water goes out from your mouth. 5 to 8 times for each side )your nose every morning and night.  I have exactly the same symptom as you do. And it works for me. At the first few times, you may feel uncomfortable. But will get used to it . I had suffered allergy for about 6 years. None of the medicines works this well for me before. Hope it will help.