Hi, I m a 48 year old woman having heart palpitations, shortness of breath, but at rest, not during exercise. Weakness , fatigue, weak legs. This has started the past three months, also sort of depressed. I m a light smoker,( I calculated I have about a 6 pack year history) and I jog 3 times a week. I m worried I have lung cancer , or is this perimenopause?