Suggest Remedy For Persistent Itchy Body Rash

I have been on prednisone for nearly 3 years following respiratory arrest incident leading to a diagnosis of adult onset asthma. During this last year, I have developed a total body itchy rash which I believe is directly related to the prednisone. I have tried reducing and getting off the drug several times but have been unsuccessful. What kind of treatment can I use to help with the itch? I have tried soaks, benadryl and topical lotions (SeraVe and Sarna). Thanks