Back hurts when I breathe...?

I had bronchitis for the first time ever this past summer. Since then I have been having problems breathing..it's been real raspy and I always cough a lot. The doctor has put me on antibiotics and steroid pills. Sent me in for asthma testing but it came back negative because she had me on a steroid! Anyways, it sounds really stupid but a few weeks ago I went to a haunted house. Came out and I could barely breathe? I almost went to the ER but within the hour drive, I started to breathe better. Well, last week I came down with a small cold and since then I am all raspy in the chest and coughing like crazy. I have an inhaler that I have to take a lot because I am always short winded. Well, today I took a walk since the temp outside was actually warm. I only walked a few blocks and then my back started hurting really bad when I would breathe and my chest hurt a little. Now I am really short winded. I called my doctor and they told me to come in tomorrow but if I keep having trouble breathing to go to the ER tonight. What could be causing my back to hurt when I was walking? It was in my upper back and it only hurt when I would breathe in.