I started to notice this in late June and early July, 2008. I spent a day or so in a place where there were a lot of smokers. Having quit smoking a few years ago, my nose is very keen to pick up the scent. It's not unusual for me to catch a whiff of burning tobacco even days after being around it. At first, I didn't think much of the smell of something burning, but as weeks went by I started to get somewhat concerned. Smelling something that no one else smells was not unusual for me since I've always had a sensitive nose, but smelling something so strongly that no one else does at all wasn't. And it was getting stronger all the time.
Researching on line, I found there were a number of reasons people sometimes smell things which aren't there: trauma to the head, severe nasal allergies, sinus infection, exposure to certain chemicals and a tumor in the brain. I couldn't think of any recent occasion I experienced any of the first four things, so I decided it was time to visit the doctor to make sure it wasn't the fifth.
My primary care physician referred me to an Ear, Nose and Throat (ENT) specialist. While he informed me that tumors are very rare, his body language and constant "hmmm, this is strange" comments unnerved me a bit. As he did his tests, we found I couldn't smell mint very well and nor could I smell lemon (I had to very deeply sniff it 3-4 times to get the scent) and my taste of salt was diminished. As we talked about my signs and symptoms, I realized I couldn't smell coffee nor taste many things. It was time for me to go "hmmmm."
Earlier this week I underwent an MRI and found out there's nothing in my head that's not supposed to be there (though someone did ask if I checked to see if anything was missing - no, I forgot to ask about that). For the week I had to wait to learn the results of the MRI I was really caught in the "what ifs" of having a tumor or not. I'm quite glad it wasn't, though I really just wanted to know what was going on.
Looking back I can see this problem probably started a long time ago. My blood pressure has been up for the past few months. I realize now I was way over-salting my food because I can't taste salt very well. I've since given up extra salt, though I can still taste black pepper so I use it. Blood pressure is down a bit now.
I also noticed over the past few weeks that if I eat very spicy food I don't smell the burning whatever as much. Bring on those jalapenos!
My advice to those who are experiencing similar problems: Go get checked out. Loss of taste and smell is common as people age. But, smelling things which aren't there could be a sign of a very serious problem. My doctor assured me that a tumor causing symptoms like mine are about 1 in 100; however, it would be nice to rule out that your in that 1%. My doctor recommended taking supplements of zinc and magnesium, which I will try. (Remember, don't try any medication or supplements without consulting your physician. I'm not a doctor, though I'm handsome enough to play one on TV).