Suggest Medication For Severe Itchy Rashes Due To Pityriasis Rosea

i was diagnosed with pityriasis rosea more than 2 weeks ago. I have a severe red inflamed itchy rash from chin to upper thighs. have finished tx with medrol dose pack with no relief. have used all types of lotions OTC-no help. Now area behind knees and anticubital spaces is burned-using silvadene. i am a nurse and understand the disease but think i have a severe case that nothing i do helps.