I would take her to the doctor because eventhough it happens earlier and earlier now a days there could be another reason as to why this is happening at such a young age.
Its it like a menstural period?
Although it is early, it is possible to begin your period at age seven.
Of course, most girls don't start tell pre-teen or early-teens, but the possibility is still there.
In my sexual identity class, we learned of women throughout the world who first got their period very early. Usually in Asian or European countries.
If it continues, and it is like a menstural period, then I don't believe anything should be done. It's just her time to begin her menstural cycles.
If it is causing her lots of pain and doesn't appear to be like a period, get in her to the doc.
Good luck and Best wishes! :)