Breast pain or nipple pain isn’t usually a symptom of breast cancer, and most breast pain is because of hormone fluctuations during your period, cysts (fluid-filled, tender lumps), injuries to the chest wall, infections or medication side effects. In rare cases, however, breast pain can be a symptom of inflammatory breast cancer, a type of aggressive cancer. Inflammatory breast cancer may cause the breasts to be discolored, heavy, swollen or painful.