Hello,
Unfortunately the picture is not very clear but it can be contact dermatitis,infected hair follicles,rash due to friction rub with clothes or 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.Also wear cotton undergarments.Application of antibiotics cream like Neosporin and oral antiinflammatories like ibuprofen/acetaminophen are also helpful.If the symptoms are severe then it will be best to consult a dermatologist
Hope it helps. Take care and pls do keep me posted on how you are doing or if you have any additional queries.Kind regards.
More like a superficial folliculitis.Antibacterial cremes help.