Just a question

People are telling me that it can be a sign of breast cancer I have not breastfed any of my kids and my third child is 3 years old and I still have discharge of breast milk and it's white it don't smell bad or anything and before you started my period it always hurts and my boobs get so sore I just wondering what do you guys think I've been to the doctors and stuff and she gave me antibiotics but nothing helped I still have breast milk and I don't understand why