I have been diagnosed with breast cancer back in 2013, no treatment for that. In October 2017 after having a mammogram my nipple turned black. I went to dr he said we will watch it and if anything changes come back and see him. Today as I took my bra off my nipple itched a little so I scratched it, sore to touch so I rubbed it a little and got a little bit of liquid out of it. What could be going on with it?