You are definitely not alone in this. Phantom smells are a documented prodrome for migraine. Take a look at this article (and especially look at the comment section that follows the article as many members share their experiences with phantom smells): https://migraine.com/blog/experiencing-smells-taste-prior-to-migraine. Thanks for your question! Warmly- Holly -migraine.com team. 
Yes, you are definitely not alone! What do you smell? There's a wide variety of experiences people have -- some of the common ones we've heard here are cigarettes, electrical/ozone smells, other smoky smells, and garbage. It's definitely a strange symptom, but I suppose for some it can be a handy clue. -Melissa, migraine.com team
