Itching on testis & penis. Solution.

Respected sir/ madam,I am facing skin disease on penis ,testis and glutious maximus & anus region.Actually inner-side of the underwere . The region where legs join in pelvic girdle,also that region itching occurs. The skin of this region already turns totally black . It starts so many year nearly 5-8 years.When itching start i used exzima /candid ointment (clotrimazole cream), it gives temporary relief.In morning when i get up from bed it gives vigorous itching.When i remove my underwear it itches vigorously . In day time every time sensation is coming in that region ,so my concentration is in that place so many times in total day.I am facing discomfort.When my concentration is in penis i face the erectness of my penis for sexual ambition.Pl give me suggestion /medication for permanent cure of this types of skin disease.I am waiting your solution.....