Thank you for asking your question on Justanswer.
These start as a severe inflamation of a follicle and become a furuncle which is a deeper type of infection and which is another name for a boil (some times called a rison) They often occur at places where clothing fits tightly over the skin, and if possible it is good to avoid this.
Some people are more prone for not completely known reasons.
Warm compresses is the recommended treatment. (Or depending where it is, sitting in a hot tob or sitz bath) When they come to a head an extra thick bandaid with while it is draining and keeping it as clean as possible with soap and water will be important.
If it expresses a green-yellow pus, this is likely staph. You may press gently to express, and you may also apply a topical antibiotic or povodine iodine. If it does not heal you will need to see a dermatologist. If you have any swollen lymph glands in the area it may be becoming a larger cyst and it is most definately an indication that you need to see the MD for oral antibiotics.
Prevention suggestions are to avoid greasy ointments, avoid clothing that is tight in that area, and wear fabrics that are breathable, such as cotton.
The complete information on treatment guidelines are here: http://www.ifd.org/protocols_bacterial.htm
The above link is the protocol for the dermatologist, so please do not try lancing these on your own.
I wish you good luck,
If you have further questions on this don't hesitate to write back. But be sure to see your doctor if they don't subside, as you may need oral antibiotics.