Suggest Medication For A Rash In My Butt Crack Area

Hi, I just finished all of my medications for my yeast infection, but I still have a rash in my buttcrack area. I did try shaving this area two weeks ago for the first time. I have been placing the cream my doctor gave me for my rash with my yeast infection, but it doesn't seem to be working on my butt area. What should I do?