Do boils and diaper rash go together?

Skin Infection: Diaper rash can be due to irritation of the skin from urine and stool, called irritant contact dermatitis. Or, can be by an yeast in the stool called minilial diaper dermatitis. If not treated, the excoriated skin may get secondary bacterial infection from the skin organisms causing boil or abscess. So, you will see both together in this case.

Not necessarily: A diaper rash is not necessarily an infection however the raw skin surface exposes the area to secondary bacterial infection. In such cases a boil can easily develop over the diaper region. If you are concerned, see your doctor for antibiotics and incision and drainage if necessary