I'm a 28 year old female. For about 3 months now, when I lay down to go to sleep, I can hear my pulse when I turn my head to either side. Lately I've been getting sudden headaches that radiate from the left side of my neck, over top of my head and down my left side of my face. Sometimes it makes my eyes water. The headaches don't last long, maybe 1 minute, but then there is a dull throb for about 20 minutes. What is causing this?