Experiencing a sweet smell like Juicy Fruit gum.

I get the juicy fruit gum smell intermittently for 12 days a year. It happens mostly in the spring. I have written to neurologists and other doctors who do sensory research and the best they can come up with is some sort of brain trauma.
This has happened to me for almost 13 years. Ther have been a couple of years in which it didn't happen, but I have no idea why. About 4 or 5 years ago I started counting the days that it existed and found that it usually goes away in 12 days just like clockwork! I know this is a weird one, but has anyone had the same phenomenon?