I am curious how fast lung cancer can grow? I had a X-ray done three months ago and it came back clean. However, I am still feeling some pain in my right lung underneath my right nipple. It's really odd, and my muscle right by my arm pit hurts, as well. Sometimes it feels like it's my pectoral muscle and other times it feels like it's in my lung. Also, sometimes there is pain in between my ribs hurt. Any idea what that may be? Could they have missed something on the X-ray?