Nipple discharge?

Af is due in 3 days! My boobs have been killing me for about a week and a half now. And today I decided to check them out in the mirror. I looked at them both and they both looked like there was a lot of little white dots under the skin, so I squeezed. Out of my left nipple 4-5 dots of white stuff came out. It wasn’t liquid. What could this be? Is it normal?