I am a 40yr old woman who had a hysterectomy many yrs ago & am having breast discomfort & greenish/brown discharge from both nipples... Why?

This is not something that can be diagnosed online. I would strongly advise seeing your doctor about this.

Please seek medical attention at once. The color of the discharge denotes infection. However, I had the same symptoms you are describing and I had breast cancer.

Please see your doctor.