Fortunately, it will get better with time but maybe you did it too drastically. Maybe you added too much decaf into the mix, or reduced the number of cups you're drinking by too much all at once and the withdrawal is too much?

I remember I went a day without coffee, but I had a 2 liter bottle of Coke. The Coke didn't help. I had to go back to bed and slept the entire day away. I'm so dependent on it, it's awful. But it's literally like a drug to me.