Why is my cough so painful in between my shoulder blades. I have COPD with pneumonia currently.

Hello. Thank you for posting.

Pneumonia is an infectious respiratory disease.   Back pain can be related to repeated bouts of coughing (resulting from both dry and chesty coughs). The most likely reason for pain is that you have strained a muscle in your back. For some people, a severe bout of coughing has been known to cause hernias or small fractures of the ribs. Chest infections can sometimes cause chest pain or shoulder pain, known as pleurisy. 

Helena