Did you replace the coffee intake with other liquids? Usually when I see people experience "caffeine headaches", they tend to be the types who get most of their liquid intake from caffeinated sources. So, they end up with a headache from mild dehydration.
I was starting my day with a pot of coffee, and water/herbal tea throughout the day. I figured a pot a day wasn't good, so I went cold turkey after I ran out; had a horrid dull throbbing headache for the next few days (thought I was coming down with something till I realised).
I'm typically not a coffee drinker but do have "binges" that last a few weeks at a time. I've actually been making sure to drink at least two liters of water a day, so that's puzzling.
