those little bumps on your areola that likely became more prominent when you became pregnant are called montgomery glands. although, i don't know who this montgomery is or what he has to do with my nipples. why are all our body parts named after men?? anyway, they secrete an oil that protects the nipple & they can become infected.
en.wikipedia.org/wiki/Glan...Montgomery

from breastnotes.com:

A number of small bumps that surround the nipple and look like "goose bumps" are sebaceous glands, and are called Montgomery's Glands or Areolar Glands. They secrete an oily substance that lubricates and conditions the surface of the nipple and the areola. This is helpful during breastfeeding, to prevent cracking of the nipple. These Montgomery's Glands become erect in the same manner that the nipple does when it is stimulated by touch, cold, fear, sexual stimulation, etc. Very small smooth-muscle tissues cause them to become more prominent (erect). This also causes the areolae to become narrower, but sexual stimulation will temporarily expand the whole breast.

probably an ingrown hair.