Kelowna, It seems strange that it is hurting like this after relatively gentle workouts...
I have not experienced this with my hayfever-asthma or my pursuiters cough (kind've like exercise induced asthma)

Is it at all possible you have pulled a muscle somewhere? Or maybe swallowed a bug and it has bruised you (I once swallowed a HUGE blowfly and after the gagging and spluttering I had a bruised sensation "behind" one lung.

Like LB, lungs are mysterious to me also...