How Can Itchy Rashes On The Body Be Treated?

My daughter, who is 43 years of age and generally in good health , developed a rash all over her body, approx 10 days ago. This rash initially presented itself as hives (pink and a little swollen) with moderate to severe itching. She was given both antihistamines as well as topical dream, without any improvement to her condition, although there was some improvement to the redness, initially. Through constant scratching, her body is now bruised in many areas and today, following a bad night of severe itching, she is now experiencing "pins and needles" sensation all over her body. We are very concerned as to what this can be and what she should do next.