Good for you to be able to quit smoking,
Do you have a substitute?
Maybe if you made some plans - about making that doctor appointment (if you continue to think that you maybe have cancer - although - why would you think so? Or make some plans or decisions about any life style changes that you can make.
That might help settle the anxiety a bit.
But if you don't really have any reason to think that cancer is a reality in your life, then get involved in some activities that you enjoy.