Milk came out of breast???

Okay so I am 19 years old I have been off of the depo shot since the end of December my period has been regular since and I have been trying to get pregnant for 10 months now but I’ve got nothing. Well my period was late by 2 days which isn’t usual at all, I took a test it came back negative, but I have been feeling really weird, I’ve been getting head aches really bad, I feel light headed and nauseous a lot of the time. Then when I was in the shower I had milk come out of my Breast. I’m not on any medications at all my period has been VERY heavy it lasted 2 days stopped for 1 day then started again. What could this be?