Sensing the smell of the smoke, when there is no reason for it (no stimuli) means experiencing a phantom smell or having a smelling dysfunction known as phantosmia.

This can be seen in migraine sufferers as a part of migraine aura, in people with seizures, or when the nervous tissue in the olfactory system has been damaged (caused by viral infection, brain tumor, trauma, surgery, and possibly exposure to toxins or drugs)
People that have chronic sinusitis or the ones with very bad cold, often smell phantom smell, or may even loss the ability to sense the smells.
Because, brain tumor can be manifested with that symptom, is good for you to visit your physician or a neurologist.
According to your symptoms you might go through a bad viral respiratory infection.
I don't want to cause you an extra worries, but some colon cancer suffers also experience smelling phantom smell as one of the symptoms.

Best wishes!
Marija