Hello,
Unfortunately I cannot confirm without examination,but it can be folliculitis,insect bite,hives,
contact dermatitis,rash due to friction rub with clothes, dermatitis (atopic, contact, allergic)or excessive sweating causing sweat dermatitis.
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.