Suggest Treatment For Rash On Scrotum

Initially I thought this problem was due of moisture but it seems that even though I take precautions it still doesn't go away and I've had this issue for more than a year now. The problem is that there is this rash growing between the crevice of my scrotum (balls sac) and thigh. What happens is that it itches down there pretty often. If I do scratch it (and usually I do because I can't hold it any longer) it doesnt bleed or any pus come out. The area will be very redish color and it has a smell of fatigus [my fiance is a nurse]. Precautions that I've taken are showering daily and washing that area with soap every time I do, and wear at least one clean underwear a day. What could this issue be caused by? Any recommendations to what medicinal lotions I can able?