Many of the descriptions here match my experience. I am 36 years old. Not a smoker, but my father smoked. I have always considered myself sensitive to smells. I hate cigarette smoke. I have a history of migraines, sinus infections (last one over a year ago) and allergies to mold, dust, and some pollens (taking meds for that.) I have post nasal drip much of the time. No one in my home smokes. There is a no smoking law in my state, so I'm rarely around smokers.
After taking prednisone for dental nerve pain last month, I started noticing a smoke smell. It's been about four weeks since I realized that there was no "real" source for the smell. My dental x-rays did not show sinus infection. I did take antibiotics for a bladder infection three months or so before I was plagued with the phantom smoke. I've taken predinose and antibiotics before without developing a noticable phantosmia, so I don't think it is the medication that is the problem per se.
The phantom smell comes and goes throughout the day and night and may be subtle or strong. It may smell sweet, like a cigar (or like antifreeze,) or stale like an ash tray or start sweet, then turn stale. At worst, I "taste" smoke or a metallic taste, like blood, with burning eyes/throat. Sometimes a breeze (eg. from the fan in my bedroom) hits at the same time, and the sensation is very realistic.
The smell can last a split second or what seems like hours, although I have not timed it. Sometimes I wake up smelling smoke, sometimes no smell until evening. I almost always notice it at some point while driving, at the computer, and while reading. The type of computer monitor makes no difference. I can also be outside and/or smelling other smells at the same time.
During an "episode," I can smell it inhaling and sometimes when holding my breath, but not when forcefully exhaling. Sometimes I can relieve it or mask it by covering my nose with my shirt or holding scented was under my nose. I've tried a nose rinse to no avail. I made my daughter check my breath after reading these posts, and she says my breath smells does not smell like smoke.
MRI showed nothing abnormal. I go for an EEG tomorrow. Last Tuesday morning, I had a sneezing fit, used Flonase, and only had one small episode that evening then no smoke on Wednesday. But today (Thursday) it was worse than ever--so bad I can "taste" it and my eyes are burning. I'm trying the Flonase again.
If that doesn't work, and the EEG does not show seizures, I'm going to ask my doctor about the antifungal medication. It makes sense that if you are on an antibiotic, a fungus could take advantage and move in. If that doesn't work, I'll ask for the antibiotics some of you mentioned. Thank you all for posting. I'll let you know if something seems to cure it.