I remember on one of my previous quit attempts, I was using some sort of program, (the name of which has slipped my mind) anyway, they said that difficult times were often experienced at three days (when the nicotine has finally left your body), three weeks and three months. I can't remember the theory behind these significant time periods but it was said to be fairly common.
Hang in there. You can do it. You need to find something else to use as a break activity. Personally, I'm sitting down with a cold bottle of water when I need that break. It's a hell of alot healthier than smoking. I hope you find something that works for you.
Cancer is a word not a sentence.