Go to your ENT and neurologist. Don't be upset with them if they find nothing--the sinuses are still a medical frontier.
One of the causes of phantom smoke smells that many, if not most, doctors are not familiar with is from an anaerobic bacterial infection of the upper sinuses. You can have this with no other symptoms of a sinus problem, as it often doesn't cause congestion. There is a possibility that you could have this, and that it is mildly inflaming some nerves to your upper lip.
I've had that smell a few times, back when I had chronic sinus problems. Here is the cure, if in fact anaerobic bacteria is your problem.
http://www.medhelp.org/user_journals/show/2322
The Flip-Turn Sinus Flush is mildly risky, because you have to bend over to do it, preferably in a shower, but you can also do it outside on soft ground. Continue to flush for a few days after the smell goes away, or it can grow back.
Like I said, go to the doctors first, and if you choose to do the Flush, use it as a last resort. And no matter what, you are not crazy.