About a year ago, I developed an annoying dry cough. I had a chest x-ray last May that was negative. Allergy testing indicated nothing, and it was attributed to prolonged irritation from the coughing itself. I also have a post-nasal tendency so generate quite a bit of mucous that requires clearing, especially in the morning. Early last week, I developed fever, chills, diarrhea, general soreness, and deepening of my cough. After a couple of days (and some Immodium), the diarrhea symptoms largely cleared. My cough persisted -- mostly coughing up clear (nothing yellow or green). In one instance, and for the first time ever, there were two or three small drops of blood. When I inhale, there is no wheezing and passageways are clear. For a few days when I exhaled, I could generate some mild wheezing but what came up still was clear. My doctor has me on five days of Zithromax (Azithromycin) and Mucinex. Over the course of the last few days, my symptoms have improved significantly. I have a sore spot in my back, which my doctor describes as a mild spasm. I am a non-smoker, have never been exposed to radon, and have no history of lung cancer in my family. Right now, I feel fine except for the cough. I have some night sweating, but my temperature is normal. How concerned should I be about lung cancer? Thanks.