What Causes Pinkish Purple And Itchy Rash Between Thigh And Scrotum?

Im males, 21, and i seem to have a rash between my thigh and scrotum on both sides, it isnt like a bug bite red, its almost a pinkish purple, and very cracked looking especially just below the base of my penis on the side of my thigh, theres a general lack of hair in that region, and its on and off itchy, and is often extremely itchy. ive been dealing with this since i was in highschool, but its getting worse. It cant be an std because im a virgin. When i was in highschool after i ran cross country, and was sweaty,there was a funky smell coming from my scrotum, and a cheesy white substance on my hair follicles. Since then the cheese has gone away but the rash from it is persisting and getting worse. Its been years now. What could this be and what should i do about it?