Having had vision troubles, due to MS, I can only say that the flare ups, lasted a couple months at a time, not a few minutes.

Glad that you will finally have an MRI, done. Someone mentioned, an ophthalmologist, have you had a recent check up or considered a neuro-ophthalmologist? Have you had any VER's done?


Edit: Oops, I mean VEP...it's been 6 years since I've had that done, so if I've made an error on the acronym, please forgive.