Going cold turkey on the caffeine is killer -- I've done it before, so my sympathies. This last time, I slowly weaned myself off and it went much smoother (I'd step down the amount of caffeine I'd do daily until I felt the headache no longer there, then step down to the next level, and so on and so forth. I was drinking over a liter of Pepsi a day when I started -- I went down to 20 oz. bottles, then 12 oz. cans, then a can of Coke -- less caffeine than Pepsi -- then a can of Dr. Pepper, then a can of A&W Root Beer -- which has some caffeine in it -- and then I was done).

So maybe stepping down would help you better?

Anyway, you have my full support and sympathies.