sounds like what this other guy posted called folliculitis (irration/infection of the hair follicule) If you shave down there this could be the cause.And if you dont,wearing tight fitting clothes like spandex,jeans or anything that causes too much friction could do it.
Sounds to me like yours is at the stage wear it has become infected if it is bloody and painful. The anti-biotics may help.But you may need a topical anti-biotic to put on the site. I have also read an anti-fungal creme may help.
If you shave,make sure to always use a new razor (at least change it once a week,as old razors become a host for bacteria) try shaving with the hair instead of against it. Avoid tight clothing/underwear. And maybe switch to cotton underwear.
Oh yeah. The skin over the bumps gets really flakely and itchy! When I pop the bumps it is a bloody puss that comes out and it is sooo painful! Then it scars and looks horrible. I have been way tooo embarrassed to wear a bathing suit for like 3 years now! I also have these same bump like things under my arms! They hurt way bad also!