A fungal infection, such as jock itch, is frequently the source of a maroon or dark-colored itching rash between the thigh and lower stomach area that has gotten worse over the past ten days, especially if there is perspiration, friction, or tight clothes. Wear loose cotton underwear, keep the region dry and clean, refrain from scratching, and avoid using lotions that include steroids since they might exacerbate the infection. Antifungal creams like terbinafine or clotrimazole typically begin to lessen irritation within one to two weeks, but if taken consistently, full healing may take three to four weeks. See a skin specialist for appropriate treatment and potential oral medications if the rash spreads, becomes painful, produces discharge, or does not resolve after two weeks.