Hi,
This could be miliaria, which may occur occur when the
sweat gland ducts get plugged due
to dead skin cells or bacteria. The trapped
sweat leads
to irritation or prickling. The papules may occur at a number of areas including the face, neck, under the breasts or in skin folds and areas of the body that may rub against clothing. Try to wear light clothing and to avoid activities that induce sweating, as well as hot and humid weather.