Suggest Treatment For Discomfort Related To Menopause

I am 52 yrs old, and the last year or so have been experiencing symptoms of menopause. I have always had a small amount of discharge (usually clear with a trace amount of green) from my left nipple ever since I stopped nursing my last child over 22 years ago. Never asked my doctor about it, wasn t too concerned then. But a few days ago my left nipple started leaking a small amount of dark blood. What could that be? Is this dangerous, and do I need to go right in to my doctor?