Respiratory Problems! Please Answer! 10 Points for Best Answer!!!?

I was diagnosed with acute bronchitis about 2 weeks ago, and seemed to be getting better. But two days ago I noticed that I had a little more congestion, and occasionally the phlegm would rattle around in my chest. This would be so extreme it would feel as if my lungs were loose. Then I began to cough up more sputum, hy and clear, but occasionally with brown flecks, but usually when I ate. Than yesterday, most of the day my sputum had brown flecks. Also my cough would worsen at night and become almost unbearable when I laid down. It would worsen to the point that I felt like gagging. Also by late-afternoon I noticed I was developing pressure or discomfort in my back. If I move it feels like a mild pain. Anyone have any idea, I am very worried. I went to the ER twice in the first week I was sick, once because I could not breathe, after I was prescribed an albuterol inhaler I was fine. The second time later that week because of chest pain, the doctor said it was because of the cough medicine so he prescribed a cough medicine and I was fine after that until two days ago. The second time I went to the hospital the doctor did a chest x-ray, it was clear. Please answer my question, and before you ask, no I am not a smoker, I am allergic to cigarette smoke. Thank You to everyone who answers my question in advance! =D