My firlfriend feeling a slight pain on the left side of her breast? what should we do?

See A Doctor: Lateral breast pain in forties female possible infectious process, which should declare with intense pain, swelling, ; redness. This region overlies the costochondral junction, ; costochondritis becomes a diagnostic candidate if focused localized pressure causes exquisite pain. Viral or mechanical etiologies are possible, ; physician exam certainly in order. Early cancer doesn't arouse pain.