I Have Terrible Itching, Which Started On My Torso, But

I have terrible itching, which started on my torso, but now has moved to my arms and legs as well. The itching is severe and I'm scratching so hard I'm bleeding in places. It seems better for short times after taking allergy medicine containing pseudoefedrine (sp?). Topical creams, such as vanicreme, are helpful for a short time only.