What Ointment Can Treat Increasing White Patches On My Buttocks That Are Painless And Non-itchy?

I have white patches on my buttocks and it seems that the patches are increasing. There is no pain or itching. First I thought it was birthmarks but it doesn t look that way. What ointment or cream can remove these patches. I m shy to consult a doctor as it is my bum area. I need your suggestions..