Cigarette smoke like smell yet no one smokes. cough, dry sore throat, nasal burns. better when outside of house. difficult breathing at times. ?

Maybe lying?: Could be that somebody is lying about their use of tobacco or could be second hand smoke exposure. Get a good history from all of your roommates.

Dryness: If you are exposed to frequent air conditioning you may be dealing with excessive dryness in your house. Occasionally asthma may present as a persistent dry cough also. Do you have any pets? Try to get rid of any dust collecting objects in your bedroom,also. See a pulmonologist if breathing difficulties persist.