I had this for a few days in the morning when I first wake up and am just sitting relaxedly. It was barely perceptible so I didn't think much of it. But this time, I was excercising and when one of the excercises required me to look down, I had this visual disturbance BIG TIME. It was like I was through a glass that suddenly gets all foggy (like when one breaths on a mirror) and then back to normal, in a pulsating fashion. It seems the pulse rhythm coincides with my heart beat. I could also feel my heartbeat on the temple area,but given that I was excercising and looking face down, this part alone would not have worried me. The going and coming of the vision really freaked me out. Since I had a more mild version for a few days, now I'm worried. What could this be?