Hello, One side breast swelling and soreness is caused by different etiology mainly include mastalgia (cyclical in young and non cyclical in menopausal women), fibrocystic disease, pre menstruation syndrome, inflammatory breast disease, trauma etc. Menstrual irregularities, stress and some medications may aggravate the tenderness. These symptoms can be an early sign of breast cancer, so consult a surgeon for physical examination and other investigations like mammography, FNAC, if needed biopsy. You should avoid high fat diet, caffeine too much salt, do self examination of breast every month. You can add vitamin E, B6 and high fibre diet. Do regular exercise, yoga and meditation also. Take care, bye.