What you are calling flashy light are what I call spots. I also can tell I am going ti have a migraine attack when I start getting this in my vision. It's either the spots or the nail that being pounded into my temple, or it's the tingliness in my neck. I can tell that I am going to get an attack if I feel any of these things/ The worse is when I completely lose my vision. (Like it's pitch black for seconds, or minutes. Up to 30 minutes!) Talk about panic and fear. But alas, my doctor (s) - eye doctor, internal med say that it's just a migraine. They checked me for glaucoma, and diabetes before they concluded it was "just migraine attacks". "JUST"...yeah...it sounds like they are JUST migraines....but it's good you are working with your doctor to rule out everything, anything else.