Do you live near a chemical plant, refinery, anywhere toxic fumes are being released? It may not be smoke as from a cigarette but some other toxin you are inhaling. Find out about the above mentioned. If none applys try going to an ear, nose and throat doctor.
Have you recently ingested any zinc cold remedies? These products can cause olfactory nerve damage which results in odd smells/tastes and even a complete loss thereof. I have olfactory nerve damage from a zinc cold remedy (cough lozenges) and I smell sulphur or burnt hair all the time. When the damage first occured I smelled ammonia very strongly.