I Do Not Suffer From Migraines As Such, But I

I do not suffer from migraines as such, but I get flashing lights - an episode usually last for about 30 minutes. I can go for weeks without any problems and can then get an episode two or three days in a row. I have pressure in my head rather than a headache and do feel tired for the next 24 hours. I have had them for a number of years. It is instantaneous and I get no warning when it's going to happen.