Breasts tmi

Has anyone experienced clear nipple dos gage from one breast. My period isn't due til the 14th but I took a pregnancy test and it says negative. I know it's early but I would say I'm not. I started lactating when I was only 1 month pregnant with my daughter. I thought maybe I was again but tests don't show anything at all. What else could be causing this. It's honestly starting to make me worry that something is wrong with me.