I used to get severe stroke like migraines and as an aura I would often smell something burning. I experience other smells when having flashbacks most notable the smell of stale beer since my childhood abuser used to reek of it. Do you ever get headaches with the smell?Or has it happened right before a seizure? My neurologist said that it can be neurological for example like a migraine, a seizure or a stroke. I would get this checked out by my doctor if I were you. Better safe then sorry. Best wishes.