What Causes Pain In Armpits And On Sides Of Breasts?

Hi for the last couple of weeks i have been getting pain in my armpits and on the sides of my breasts. i think i had flu 2 weeks ago as i had a really bad cold and cough, coughing up green mucas and for 2 days all my muscles ached. My armpits and my breasts have no lumps and are not swolen from what i can tell, and the pain is not constant, it comes and goes. i was also diagnosed with a disease that i cant remember the name of, it began with b and it was inflamation of the ribs from a virus i had recently got over from. I still have this. are you able to tell me if this is something to worry about. i am female and 24.Thank you.