My first guess would be mites, and she really needs to see a vet. Both for mite treatment and to get her checked out given her ordeal. If you do end up taking her in or getting mite treatment, make sure you give her Revolution (called Stronghold in Europe). Don't use Ivermectin (sometimes called Ivomec), it's easier to overdose & has been deadly for hedgehogs in the past.
Can I ask where you're located? I'm really happy you guys found this poor girl! But it sounds like you might not be in the best situation to provide for her, if money is tight. Hedgehogs can rack up vet bills quickly when they get sick, and exotic vets also tend to be more expensive than typical dog/cat ones. The Hedgehog Welfare Society might have a rescue station near you that can help out with her if you guys can't afford the vet bills & everything.
~*~*~ Kelsey ~*~*~
RIP my sweet Lily ~ 6/12/08 - 1/20/12