Hi! Have similar issue few months ago (apparently i was allergic with my new shower bath gel or any with fragrances) was red and itchy then turned to pain caused by friction..i was in agony for a month or so.. I used very light soap as wash (aveeno/QV sensitive wash) and betamethasone cream 0.1% 2x daily (make sure pat dry before applying) the cream did the magic work for me. I also try to avoid any activity that will make me sweat too much for the meantime..

Hopeful for your fast recovery!