What Causes Persistent Itching Under Arms, Breasts And Abdomen?

I have been itching under my arms, under my breasts, under my stomach, in crevices of my upper legs, I have NO rash. I have taken Oatmeal baths, used A & D ointments, used bendryl cream, nothing helps. I do not use soap or detergents with perfumes or dyes either. Help?