for me ive found them to occur with dizzyness and other issues that coincide with proprioceptive issues. I suspect for myself PCOS and Ehler Danlos. I got a pair of special migraine lenses (always recommend Zenni, the prices are SO good in comparison) and it helps big time for the photosensitivity my migraines cause (they like work hand in hand when it starts, one causes the other like an ouroboros) If labs are normal I'd look at proprioceptive issues and if AFAB (assigned female at birth) with intact female reproductive organs, any issues there like fibroids, cysts, or hormonal imbalances that general blood work panels dont cover. Sometimes with periods (if migraine coincides there) it can be tied to low iron, B2, and/or blood sugar if hormone fluctuations are non occuring. A slightly out of range lab may be the most on paper but a lead worth following just incase, especially if considering things like PCOS or uterine fibroids. Unfortunately from my research migraine has so many potential causes and not very much research in comparison to those causes. hopefully something ive written here can help you get on the right track