Breast :: Dark Green Discharge When Squeezed

For the past three weeks my right breast has been leaking a dark greenish thin liquid when squeezed. I first noticed it during my menstrual cycle and thought it was just my hormones going crazy, but it hasn't gone away after my period ended. I don't feel any unusual lumps. But I do feel a slight pain, though I'm not sure if this is jut because I've been thinking about it so much. (Kind of like when you think about your feet and they start to itch.)

I also have bursitis in my right shoulder, which sometimes causes sharp pain in my pec muscle. Could the discharge in my breast be related to my shoulder injury, or is it just a coincidence?

My mother had breast cancer (is healthy now thankfully), so I am very worried. I am only 24 years old.