Should pass in 4 - 6 days. I had what I can only describe as a migraine when I gave up caffeine which lasted for 4 days. Really painful. I also had quite bad stomach cramps and, strangely, sore quads and thighs. Felt as though I'd massively overdone a training session (which I hadn't!)
Mr. Yoyo suffered this about three years ago when he decided to give up coffee. He was in such a state he couldn't sit still. I was inwardly frantic but remained cool when I suggested that the two/ three cups a day he consumed weren't that harmful and why give up something he enjoyed in moderation? To my enormous relief his response was to go make himself an espresso. His recovery was instant. He has been drinking coffee ever since.