Suggest Treatment For Itching Rash On Rectal Area, Buttocks And Waist

WF, age 64, HTN,with red itchy rash that started on rectal area with bump and has gradually spread to buttocks and now is going up back and around waist. First thought it could be yeast infection and used Monistat. Went to ER two days ago and got steroid shot, atarax, Zyrtec, and Pepcid. Using Cortizone Plus 10. Any other suggestions? Have follow up appt with family physician tomorrow.