There's an old story about a guy who goes into his doctor's office and says: "doc, it hurts when I move my arm this way" The doc looks at him and says:"Don't move your arm that way."
Sometimes the simple solutions are the right ones
Seriously - you described the possibility of a very serious condition, and it stopped presenting very fast, which is odd, and showed no other symptoms - to me the first thing to to is look for the obvious answer, which is often a non medical one - a lot has to happen to you to have SE, and before jumping to that conclusion it makes sense to ask what other factors are involved. The greatest problem with the Internet, IMHO, is that we see way more "med school syndrome" patients than ever - they get a little something or other, probably innocuous, look up that symptom, see a link to other things, since the search engines don't filter things according to logic but how many times it is hit on, and jump to the worst conclusion. They come into us with a foregone conclusion, forcing us to think along those lines, and sometimes we miss the real problem, which might either be nothing serious or something even more serious that could have been caught had they not come in with a diagnosis already - I force myself to NEVER listen to any diagnoses from patients so as to have fresh ears and eyes for the real evidence.
Keep your appointment. It would be wise; and ask for an Emphysema test anyway, just in case, but I am glad that it was something way more simple.