Long lasting sinus infection

I don't have allergies and don't have a cold, but I get so congested. Usually its just one side of my nasal at a time. When I'm up and moving around it clears up a little, but if I am sitting or laying down its terrible. No headaches from it, but it is completely "clogged". I have tried saline nasal spray and went to my doctor when this started and he gave me Allergen or something like that and it didnt do much at all. He also said it could be because of the heating in your home. But we havent had the heat on considering its summer now and its worse than ever. I am just looking for answers, any suggested medications or alterations i can make at home to help clear this??