HI, I HAVE A HEADACHE THAT COMES AND GOES...IT STARTS AS MILD RADIATING PAIN ON D BACK OF MY HEAD NEAR MY NECK THEN PROGRESSES TO BECOME SEVERE PAIN THAT RADIATES BACK AND FORTH BETWEEN BACK OF HEAD TO UPPER LEFT SIDE OF MY HEAD. DURING THIS TIME I FEEL STRONG JITTERS AND MY VAIN ON D LEFT SIDE OF NECK AND HEAD (BY MY TEMPLE) PULSES SO STRONG THAT IT S VISABLE WHEN SOMEONE LOOKS AT IT. WHEN THIS HAPPENS I HAVE MILD BLINDNESS IN D RIGHT EYE THAT ALTERNATES FROM BLURRY TO BLACKNESS. THIS HAPPENS FOR A GOOD 5-10 MINUTES WHEN IT HAPENS THEN GOES AWAY COMPLETELY LEAVING ME WEAK AND WITH SORENESS ON D TOP OF MY HEAD. ANY IDEAS WUT COULD BE TRIGGERING THIS???