As the title says, this is just a guess and if you are really concerned, or your ball's conditions deteriorate, then take her to a vet.
It looks like to me, an injury consistent with extremely high belly heat. Typically when you see a ball that has been burned from high heat there is a noticeable line down the center of the belly and almost looks like a knife cut.
As far as the scales go, if a ball sits for any length of time on substrate that has urine in it, it can cause scales to rot/burn and actually creates blisters. That can be helped with repti-wound from reptile product suppliers.
Again, without knowing what exactly your setup conditions are, everything is just a guess. Hopefully that helps and let us know how it turns out 
Jeff
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