What are these sores on my waistline?

They're around my belly button. They start off looking exactly similar to zits.. then they achieve bigger until they turn into open sores. Then a scab forms. Then it newly turns into a purple circle type thing. Then when I rub it beside my finger, it literally feels approaching I lost some skin behind it (it description of feels resembling a hole) (this process takes a week)

I asked my doctor what it be last year, and she said it's newly from the waistline of my pants rubbing against my skin. But I deduce she's wrong. Any help would be GREAT!!
Answers:    perchance an alergy to the metal button back of your pant? i know a girl who get sores from buttons and snaps on clothing.
i have that it's soooooo gross put some rubbing alchol on it and a bandaide does it feel approaching a big zit under the skin rationale yea it'll go away