Why Do I Have Increasing Pain In My Right Armpit When Breathing, Along With A Persistent Cough And Nausea?

Hi,I have cough since 2 months now and still my treatment is going,I always have vomiting feeling when I cough and sometimes after eating I immediately vomit,well that is getting better,I am taking steam everyday as prescribed,and a tablet ventidox, but there is a pain in my right armpit whenever I breath the pain starts and now the pain is slowly increasing