How can I stop my dog from ‘digging’?

I have an indoor dog. Female boxer german shepard mix - about 6 months old. After having her fixed, all she does is dig at things. She isn't hiding anything when she does it. I can't figure out why she's doing this or how to stop it. It's too cold to put her outside, but she tore my bed completely apart today. Why does she do this and how can I stop her?