Based on the history you have given it might be a unresolved sinus infection which might have happened by stopping medication without completing the schedule you have been prescribed or by having shower in a unclean water. Sometimes this might be due to allergy to dust particle, fan generally recirculates the air in the room,if you are not sweeping your room properly, switching on the fan makes you to inhale the air containing this dust particle. So try to clean your room including the fan, all you need is a fresh air while sleeping. Do morning brisk walking and breathing excercise to develop stamina for your allergies. If you are not satisfied consult a physician.