I've been having trouble breathing recently and went to see the doctor. He asked me to get an X-ray of my chest and face. The report said my lungs are clear, but I have a lung infection and sinusitis. I'm still struggling to breathe. Could this be small cell lung cancer? I have some symptoms, except for weight loss and coughing up blood or phlegm. It's been going on for a month, even though I'm on meds the doctor prescribed. Should I be worried?