Hi. I was feeling fine until Saturday early afternoon. When I left my place and started walking towards the subway, I felt a sharp pain on my chest and almost like I had a fist on the right side of my back. It wasn t incapacitating as I still managed to get all my things done, but still was uncomfortable. When I bend down, I feel like something is moving. I do clear my throat every now and then ( But then again, I had a cold about 2 weeks ago ) I don t really feel much if I sit down, lay down or stand up not doing much, but if I go out for a walk, the discomfort comes back. I m just getting a little freaked out that it may be lung cancer or a collapsed lung or something like that. Although I haven t been spitting out anything weird up to this point and my appetite is the same.