Hi there, Thanks for your query. The smell of sulfur without there being any source, is usually a manifestation of a chronic sinus infection, nasal tumor, after head injury or a type of epilepsy. You should not take it lightly You will require an MRI and EEG to identify the exact cause of this smell hallucination. It is called Phantosmia. Consult your doctor and apprise him of my opinion. I am certain that he will agree with me, order the required tests and- based on the reports- will reach to a definite diagnosis. A specific treatment of the diagnosed condition will relieve you of the problem. If you find my response helpful and informative, do not forget an “excellent” (5-star rating) to my answer, to ENCOURAGE ALL doctors- engaged in social service- to render sound advice to the FREE queries. Take care Dr. Rakesh Karanwal