Over the past 7 or so years,occurring 1 or 2 times a year, a popping sensation at the base of scull, followed by a feeling of heat and about 10 seconds of excruciating pain, so severe it would cause fainting if it lasted longer, a white out in vision, can t see anything, what could it be..... no other healthth issues....run and lift weights regularly,health diet, low in fat and sodium, moderate alcohol use