If both these possibilities are ruled out then other possibilities causing similar symptioms like fibrocystic breast disease,ductal ectasia,mastitis(inflammation of
breasts),galactoceles,benign and malignant pathologies of
breasts,referred pain from liver or musculoskeletal system,arthritis of the ribs,costsochondritis and inflammation or sprain of pectoralis muscle have to be ruled out.
Hope this helps.