Kaleidoscope Vision

I've had chronic migraines since I was 15 without aura. I am 46 and suddenly 6 months ago started having kaleidoscope vision. It was in my left peripheral field, lasted 30 minutes and I did not get a headache. It was scary as I have not had vision issues before. It would happen every 2 weeks for a couple of months, then weekly, now it is every few days. I can not see when it happens. I made my MD aware and he ordered a head MRI. I will be getting it next week. I never develop a headache with it, it typically resolves in 30 minutes. Has anyone experienced this? I'm wondering why this has suddenly started?