how do i treat this rash?

ive had a non itchy red rash thats just real sensitive around my groin area …im pretty sure i got it while i was hiking a week ago…the friction of clothing and sweat caused it… the problem is im not sure how to get rid of it…im in the military about to deploy so i cant just stop training …we run everyday and im usually walking around all day…i tried using arm n hammer body powder but this past week it turned into a mild open sore..what can i do? serious answers only please thank you

you might not think this is a serious answer but it is use the same cream as mothers use for nappy rash it works been there done that it is basically the same rash