I used to be a smoker, but only for a few years. I am 24 and don't feel that the amount of time that I smoked should have caused the condition that I am experiencing. Lately, I have had shortness of breath where I feeel like my lungs are incapable of fully filling up with oxygen. Also, I am having trouble yawning. By this, I mean that i will start what feels like a yawn, but the full yawn is never completed. I believe this could be psychological, but am not sure. Can you tell my what respiratory conditions, ailments, disorders, etc. that I could be experiencing? Thank you.