25 years old, quit smoking for 1 mnth, sob, intermittent chest pain that moves, doctors say lungs sound clear, no, cxr lung cancer??

Not cancer. Congratulations on your smoking cessation. Lung cancer doesn't present this way. The pain is almost certainly chest wall pain, but if you are really short of breath as well (and it's not just from discomfort), you need a competent fitness evaluation and perhaps spirometry in addition to your CXR and exam. Adult-onset asthma might be the explanation; it's manageable. Best wishes.