Hello, Rashes on skin commonly occurs due to side effects of medications, allergies, eczema, autoimmune conditions, psoriasis, contact dermatitis or shingles. Since antihistamines and steroids are not working. You are suggested to have a clinical examination by a dermatologist done. You may have to get blood test, test of an area of the scaly or crusted skin, skin biopsy & STD tests done. You will be treated with antivirals or antibiotics depending upon the severity of the infection detected. Stop taking any food that causes allergy, medicines causing side effects & reduce stress. Avoid alcohol, smoking & addictions if any. Avoid too much exposure to the skin, wear loose fitting cotton clothes. In the meantime you can apply Crisaborole (Eucrisa) ointment locally. Phototherapy in also an effective treatment. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Nupur K, General & Family Physician