Back hurts when I breathe....?

I asked a question a little bit ago about if people think I might have asthma.. some said yes, some said no. I got bronchitis over the summer and have had trouble ever since. A few weeks ago I took a walk in the cool weather and my back started hurting bad when I would breathe in.. I called the doctor and they said to make an appointment the next morning if it still hurt but if it got too bad, I needed to go to the ER. Well, it stopped hurting so I figured it was nothing... Well, last week I got a cold.. Since then, I wake up and it feels like a brick on my chest, I have a lot of mucous, and coughing a lot.. my chest is really wheezy and raspy.... and tonight my back is hurting bad when I breathe... Could it be caused from coughing? or something more serious..?.. I wanted to ask on here first, but I thought about going to the ER....