Well, from your description, I have to tell you that you may suffer from ocular migraines, which is also called as painless migraines. And for the causes, according to some researches, stress, too much caffeine, too much or too little sleep, weather changes, altitude, certain foods such as cheese, chocolate or wine can just cause it. And because of that, you may suffer some other symptoms, such as attacks of dizziness, hearing or vision disturbance, sensitivity to light or sound, nausea and vomiting. What is more, you may have trouble in speaking or understanding speech. So for the sake of health, I will suggest you go and see the eye doctor as soon as possible.