How can I get rid of brown blotchy skin stains on my stomach?

I am a young female and I decided to shave my stomach because all my other friends do it, so I didnt think there was anything wrong with it. My stomach was fine for like a month. Then, I started getting brown blotchy stains above my belly button. Now it's like a long brown blotchy line above my belly button and it won't go away. The stainned skin is also VERY dry. I tried hydrocortisone cream, but that made it worse. I also tried cocoa butter cream, and that doesn't work either. Washing it off doesn't work either. Help me please. I really need to get rid of it.