My Newborn Has Pimple Like Bumps That Are VERY Tiny

My newborn has pimple like bumps that are VERY tiny on her belly, with a white line in the middle almost like dry skin, When I squeezed the bumps gently some fluid came out but did not bother her, they looked kind of welted. One is above the belly button, the other is inside of her diaper area near her leg and a bigger one (still small) on her back. What could this be? Her pediatrician didn't know as the white line (feels like dry skin/scratch_ threw her off.