I don't know why, but try painting iodine on it. You can mix with a little Vit.C to make it clear so you can paint regularly. Be sure and paint it over that cheek as well which is the sinus cavity associated with that nostril. It might be a deviated septum, but it might also be a fungus infection. I painted regular Lugol's solution on my sinus cavities (facial cheeks area). I knew which side was the culprit because the color from the Lugols totally dissappeared in 2 hours. And yes, my clogged head improved! The other cheek took 8 hours to go away. But by mixing with Vit. C in a little water, you can keep painting. The Vit. C also gets absorbed! One time the Lugol's color suddenly appeared so I knew that the Vit. C was absorbed faster that the iodide. I put a little more Vit. C in water on the areas and the color went away and stayed away.