What Causes Foul Smelling Nipple Discharge?

Hi, I've had a breast biopsy around my right nipple in 1997. Am 47 female and ever since that breast gives off an off-whitish smelly discharge when I squeeze the nipple. lately it itches around the nipple and sometimes feels like the whole breast. I had a momogram about 6 months ago and it was fine, except for some Ca spot which I was told were normal for my age. should I be worried?