It looks like she underwent a severe weight loss, as she does look pretty emaciated (spine showing and "side suck" as I like to call it). If she is eating small rats keep feeding her those every 5-7 days. Hopefully as she gains weight it will go away. As long as she is eating and voiding regularly she will be just fine after putting on some size. If it does not go away after weight gain; don't feel bad, be happy knowing you nurtured her back to health and gave her a better home!