I started suffering from phantosmia early this year. Initially, the smell of cigarette smoke was faint. Then when it came back the following month, it was with a vengeance. I could not sleep because the smell of smoke was giving me headaches and was drying my mouth. Nasal washes and dabbing tea tree oil provided only temporary relief. I also had a brain MRI which was negative. I tried them all. What we all have in common are allergies, sinus problems, possible depression, and yeast / fungal infections?
I did not want to take any more medication since they tend to only do harm, if not now, then eventually.
Something told me to deal with the depression first. I was not clinically depressed since I still functioned well at work.
I decided to try herbal supplements. I was going to take antidepressants only as a last recourse because its habit forming. I bought St. Johns Wort (herbal supplement alternative to antidepressant since it uplifts mood) and garlic supplements. Garlic is the best natural remedy available since it is antimicrobial, antibacterial and antifungal. I took the highest dosage of garlic available (odorless 1000 mg) and the highest dosage of St. Johns Wort (with "hypericin"). I did not notice any change in smell the first 3-4 days, and then the smell started getting fainter and fainter. About a week and a half later, the smell disappeared. It's now been three months and the phantom smell hasn't come back.
Try this over the counter remedy. I know the hellll that you are all going through and I just have to put in my two cents. The combination of St. Johns Wort and garlic helped me. Give it a try!