Headaches While Sleeping

I am a 20 year old female college student with no medical condition besides asthma. I have these headaches that only appear when I am sleeping. The symptoms are I hear some kind of ringing then a flash of while light. I could not move when this is happening. Some times I could hear voice when I see the light. When it is done I could only move my eyes and see lights dancing in front of me. I stay paralyzed for a moment and would be able to move. However, I only move for a few seconds and just fall back to sleep as if nothing had happened. I know it was not a dream because my head hurts when it happens. It’s always random so I don’t know when it would happen. I went to the doctor about it and done all kinds of test, but found nothing but a sinus infection in my brain. I ask if this was the cause of it and they said may be, as if they didn’t not know for sure. I looked up online if it could. Although it can cause headaches, it didn’t have the symptoms I was getting. A few months had past without these headaches and I just brushed it off; however, a week ago I had it again. I just want to know what it is.