Hi, normally air is inhaled more from one nostril compared to other for few hours which is followed by repeatation of the same thing in the other nostril for few hours, which is a normal cyclical phenomenon observed in humans. Based on your history I think you are a person who sleeps with turning on your fan, generally poor sweeping of the floor or sleeping in a unclean room will result you in inhaling the dust particles when you turn on the fan. So I suggest you to get the place you sleep clean properly including the fan. Get a allergy test done to know about the things you are allergic to and avoid coming in contact with it. Do daily morning brisk walking, breathing exercises and meditation to build stamina. If you are not satisfied kindly consult a physician or ENT specialist.