Hi, recently been having shortness of breath and tight chest problems that came in very suddenly. I smoked for 20 years, quit 2 years ago. Been running 25 miles a week since. Never felt breathless until suddenly 6 weeks ago, and hasn't gone away. Due for pft and spirometry next week. Could this be copd? I'm only 35, and before now considered myself to be very fit. Can this manifest so suddenly? N.b. 2 clear chest xrays in the last 6 weeks. I've also had rib pain across my chest the last few days. Not sure of the significance. Peak flow of 700-750.