Your trip to the ER must have been scary for you. Sorry you are going through all this. I only have the shortness of breath upon breathing if I'm having a bout of pleurisy. I haven't had that in more than 8 years though.
Sounds like you might benefit from having a chest xray done.
Good that the prednisone worked for you. That's a pretty good indicator that you have inflammation going on. I hope you get some answers soon too,