Without examination,confirmation of a diagnosis is tough but it can be folliculitis, contact dermatitis
,rash due to friction rub with clothes, dermatitis
(atopic, contact, allergic)or excessive sweating causing sweat dermatitis.
Folliculitis is the inflammation of one or more hair follicles. The condition may occur anywhere on the skin.
Folliculitis starts when hair follicles are damaged by friction from clothing or blockage of the follicle.