On rare occasions, I've had migraines be preceded by a white dot in the middle of my vision that then expands and has polarized edges. By rare, I mean it has happened only a couple times in the past 10 years. Have you ever had such a striking uptick in the frequency of your migraines? If that's not part of your long-term migraine history, I think I'd want to see a doctor, and especially if there are new symptoms you've not had before. Hopefully it's nothing to worry about, but better to be safe!
All the best,