cluster headaches
"I first experienced cluster headaches when I was 20 years old.  Never felt anything as severe in my life.   The first experience was pure hell, and unsuccessfully treated.  Thankfully they subsided after a month in a half on their own.  3 years later (almost to the day) came round 2.  This time, new doctor prescribed verapamil.  Virtually made the headaches disappear within 48 hours.  Had to stop taking the medications once a week to see if they were gone so I could discontinue the use of the medication.  Been through this cycle 4 times now, and verapamil has had the same results each time.  Frequency is the same, length of cycle is the same, and pain is the same... But as soon as I get on verapamil, It's almost like not having them at all."