Shortness of breath is a common symptom that may come on rapidly or gradually. If you are experiencing shortness of breath, that does not mean you should necessarily be worried about lung cancer or serious conditions such as heart disease—but you should see your doctor as soon as you can.
There are many causes of shortness of breath, and they are treatable. You will need to talk to your doctor, have a physical examination, and probably diagnostic tests to learn why you are short of breath.