Milk blisters (blebs) hurt SO FREAKING BAD!!! Omg. I noticed a yellow spot on the underside of my nipple 2 days ago. At first I thought it was a sore from where my baby bit me a few days ago, but it turned into a yellowish pimple like thing. After some research I found that it's a milk blister. And man does it HURT. I hope anyone who breastfeeds doesn't get one. And if you ever did have one then you feel my pain!