The last two times I was in Spin class I felt a slightly sharp pain in my lower right lung in the back by the ribs. I used to smoke heavily until 2002 and stopped for 7 years. I am embarrassed to admit that since 2009 I have picked up a butt here and there. The instructor thought it could be dehydration and it did go away after I drank coconut water. I have minimal parenchymal scarring so I am concerned. I also stopped completely smoking recently. Does anyone have any information or experience with this kind of symptom?