Hello, I Have An Itchy Rash All Over My Body

Hello, I have an itchy rash all over my body and on my scalp. I am much more tired than usual and am very light headed. My bowel movements are very inconsistent and I am bloated. My GP said it could be eczema or emphysema (though I am not breathless at all) and gave me steroid tablets and a steroid creme which stopped my symptoms, but it all came back after a week and my GP said it wasn't safe to give me any more steroids. I was given antihistamines, but they made me very dizzy so I can't take them. Do you know what could be causing my symptoms and what treatment options I could try? TIA