Cluster of pimple looking bumps?

My 12 year old daughter broke out with a grapefruit size cluster of pimple like pumps on both sides of her bottom. Some of them have white heads on them others are red. She she says some of them hurt when i touched them. they are raised like a pimple. Any clues what this is and how to treat it.|||Take to doctor. I had the same symptoms...it was a staff infection|||Go to a doctor with her.