The longest I fasted was 8 days. I quit because of the severe head pain each time. Don't give up! What comes after the head pain has got to be very rewarding. I believe that the pain is a sign that you really need to continue. Ice packs provided me with some relief and I also found some relief by using a hand-held massager on my neck (on high-speed). I wish you the best of luck! Keep going!
Diane