I can relate to a lot of the same symptoms that many of you are experiencing.
I am now eighteen years old, my breathing problems started when I was in Grade 10, a couple of years back. It happens at random intervals. Sometimes I can go months at a time without having the slightest issue, but it has just gotten a lot worse. I yawn repeatedly, unable to "complete" the yawn by breathing deeply for a minute or more, and until I complete the yawn by inhaling deeply, then exhaling, I can't breathe at all.
When this first started happening, my doctor sent me to all sorts of specialists. I had my bloodwork done, a CT scan, a lung scan, wore a moniter that marked any and all changes in my lungs and heart when I breathed for a week, and all of these showed nothing. Finally, having a drastic attack, I went to the hospital, and underwent numerous tests, including repeated bloodwork, and it showed nothing.
My doctor prescribed a Ventolin diskus, which sometimes helps a little but not really. I also went on hormone pills, in case it was hormone related, but they havent helped. My doctor seems convinced that it is anxiety, but I know it's not. I don't smoke.
Has anyone found any way to cope with this? I'm deeply concerned.