What Causes Severe Pain Under Chest, Cough And Breathlessness?

Hi, I have been suffering from severe pain in my diaphragm from past 15 days. In addition to this i have coughing and breathlessness from almost a month. The pain in the diaphragm shifts to lower chest pain and switches between left and right side. The pain is also extended towards the back. I have taken a course of antibiotics named Augmentin and painkillers for 10 days(thrice daily). The pain was better with the medicines and recurred on completing the course. Please provide details of the possible problem based on the symptoms and necessary treatment.