This white bumps that you have on your areolas are a very common and do not represent any serious medical problem. What they are likely to be are simply normal glands in the skin that produce lubricating substances. These glands are always present, but sometimes they can becomes either plugged with dried secretions or they can become larger under the influence of hormone cycles (such as occurs with the period). Therefore, it is really quite normal to see them come and go, or at least get bigger and smaller, from time to time.
The temptation may be to pick or squeeze them, but this should be avoided as it will just tend to irritate them and may predispose you to a skin infection. Gentle exfoliation and cleansing may help to keep them open and reduce the size.
If they get much larger, of if there is any pain, redness, or swelling, then these might be signs of an infection. If you think you may have an infection, you should go to see your primary care doctor
, who will be able to determine if you need treatment.