Hi.. Thanks for the query.. Constant smell of tobacco through nose that is not exactly present seems consistent with a condition known as Phantosmia.. It can occur due to a number of conditions like nasal infection and polyps, migraines, Oral and dental infection, smoking habit, condition related to Nervous System like Parkinsonism, Alzimer s Disease, Stroke, head injury etc.. I will suggest you to consult an Emergency room and get evaluated and along with clinical evaluation investigations like Nasal endoscopy, MRI, CT Scan etc can help in diagnosis and treatment can be planned accordingly.. As of now you can do saline nasal irrigation, steam inhalation with few drops of Eucalyptus oil in water,chew flavoured sugar free chewing gum and limit intake of high aroma foods like onion and garlic.. Hope this helps.. Regards.