Hello,
Without examination, confirmation of a diagnosis is tough but it can be due to contact dermatitis,sweat dermatitis or heat rash.
Wash the areas several times with fresh water. Do not use any cosmetic products at the sites. You can apply some calamine lotion at the rash as it will help in soothing the skin. You can take some OTC oral antihistamine medications like Benadryl or Claritin if the blisters itch.
If still the symptoms do not improve or turn painful then pls get a clinical examination done by a dermatologist.Herpes blisters have to be ruled out.
Hope it helps.Take care and pls do keep me posted on how you are doing or if you have any additional doubts.Kind regards.
Apply calamine,if persists consult you doctor.
Herpes Zoster is a possible diagnosis.Irritant dermatitis is another.