Well the good news is your symptoms seem like anxiety. I've had actual asthma when I was younger, I haven't heard of anyone dying from it, especially since you haven't mentioned any allergies. I've never had that sensation during my panic attacks...but perhaps this will help.
w w w. panicaway.c om/anxiety-symptoms/anxiety-breathing
Good news is you probably don't have lung cancer and considering you're probably younger than 30, you definitely don't.