Suggest Treatment For Skin Irritation In Groin And Buttock Region

Hi im a 24 year old Male who is 6ft and around 80kgs.. I have over the last 6 or so weeks obtained an irretation on both sides of my groins and also my bum crack. It is worse some days then others when it turns to be a brighter red and becomes a bit more itchy.. I have tried some anti fungal cream and that just gives some short term relief from it being a bit itchy... I originally thought it may be a heat rash as im very active and its been hot but in more recent weeks the weather has cooled.. Where should i take it from here?? Thanks Heaps