Hello,
Your initial description of symptoms in association with a
migraine headache that you've noticed may be some form of unusual aura since migraine
headaches can be preceded by such symptoms.
However, in your case, 3 days is quite a bit longer than what is generally accepted for an aura which is at most 60 minutes prior.
Still, in order to really know what the timing of these events are along with any headache that follows you'd have to keep a journal.
Now, that you are not having headaches but there is this persistent symptom of an odor you may wish to get a neurological examination by a specialist.
They may order an imaging study of the brain (
MRI with gadolinium would be my choice) since there are such things as benign tumors (meningomas) that can impinge upon structures in the brain (olfactory bulbs) having to do with the sense of smell.
It certainly doesn't sound like anything dangerous but since there is a pattern you've recognized it's worth looking into a bit since there may be an easy fix.
Hope I have answered your query. Let me know if I can assist you further.
Take care
Regards,
Dr Dariush Saghafi, Neurologist