i had the itch, the dryness, and redness (cant say that it got darker) went to the doc, and they said i had "Jock Itch"
Treatment for that is 1st, is fungal, so it likes sweaty, dark, moist area
so you gotta make the opposite for that down there (cant help you with the darkness though, lol) just keep showering but pat that area dry, and keep it dry
worked for me in about 4-5 days
just trying to help..