My aunt is 45 and she is breast feeding. she started to feel a pain in her right breast and there is a lump there. what can it be?

See the doctor...: In a breastfeeding woman with a painful lump, i would look for mastitis (breast infection) - women can get ill quite fast, with a high fever. It might be a blocked milk duct. But my real concern is that any lump in the breast could be a cancer. Please encourage her to see her doctor about this. An examination - and perhaps an ultrasound - would be very reasonable here. Good luck. Lgromko.