I had coughing/congestion for a week. now there's back pain under right shoulder blade. only hurts mildly with deep inhale. nose is still stuffy.

Should get x ray: There are several possibilities one is that all the coughing caused a muscle spasm and that is what hurts. It could be pleurisy a bit of fluid in the membrane around the lung. It could be a pneumonia although that's normally not painful but you may notice a full sort of breath feeling in inhalation/ the xray will rule out a lot of these quickly/.