I have tracked my episodes for almost 9 years.
My sinuses get congested or I start to get a sinus cold and sure enough
when it happens it is related.
That is it for me. No other occurrence other than occasionally a mild related 'sinus-like' headache, maybe optical. If it is a migraine it doesn't feel like one.
When I first started to have them I thought it was because my work requires me to be on the computer most of the day and night. But doesn't seem to be related. But optically certain colors like bright yellow in my graphic design work sometime created a momentary optical disturbance when working at night. The screen is bright and the yellows are even brighter and I can't afford a $300 pair of computer filter glasses.
Like I did, diligently keep a date log every time the episodes occur. The time of day, the length of the episode, what you ate before, what you were doing etc. You will soon find something related...including diet or other.
Be Well. Don't let anyone put fear in you. You are your own best observer about
your own habits and if you pay attention you know your body better than anyone else.