On And Off Severe Headache With Zigzag Lines In Front Of Eyes, Virtigo. Suggested Possible Lack Of Blood Circulation To Brain. MRI Scan Normal. Opinion?

Hi Doctor, since three years I am feeling severe headache periodically, once in a 6 months or 4 months, it is like this, some zigzag lines will appear infront of my one eye's sight area and a feeling of lightheadedness. It will be around 5 minutes. After that I was feeling hectic headache and nuesia. After 2-3 hours I will be alright. I consulted with a neurophysician and he said it is because of lack of blood circulation to the brain and preescribed some medicines. Some 4 months back when I woke from the bed I had a feeling of vertigo. It was for just 2 minutes. After this continously I am feeling lightheadedness. I have done all kinds of check ups including brain MRI scan. Doctor said everything is ok. But same thing is continuing still. When I wake up from the bed everything will be alright. But gradually this feeling is increasing. By afternoon it will reduce and headache will start. By evening I will become ok. What is this doctor? Is it migraine? or is it sinus problem? or some thing other? I am in quite dilema. Please help me.