have you gone to your gyn and did they do a slide of your discharge? If not that would be my next route to take. It may be a backed up duct in your breast.
It could be a number of things. My guess is a backed up duct or two. I would go to my gyno. They are usually more concerned and a lot more helpfull than anyone else. In my experience that is.
Did you maybe breastfeed your children? I know for me, I breast fed my children and I still can get "milk" out. I guess that is what it is??? I breast fed my oldest for 20 months, my second for about 14 months. My oldest is 7 and my youngest is 3. You would think my milk would have dried up by now. I assume that is what mine is. It has never worried me nor have I thought too much about it.
If you haven't breast fed, I would difnitely go to my gyn and talk with him or her. Go to a gyn doctor, someone that specializes in women's health. They know more of what is going on. They deal with these issues daily.
Hope to help!
when this happened to me (not that it is your case) my dr said this can be normal. by continuing sqeezing them and checking you are keeping the fluid going. im not saying ignore it just giving you a sample of what i know lol.