Hello, my dog went through that stage already. I have a huge solution that I did and taught my friends to do. First, do you have a big area space where you can let you dog dig in the dirt? If so, then put your dog on that area and let her dig. It's that simple. Hope this helps a lot.
I've heard too that giving them somewhere where they can dig can help - some people use one of those sand pits. Something I heard on the radio a while ago intrigued me - someone had the same problem, and buried a balloon in the ground where the dog was digging... needless to say, after being scared by the balloon bursting, the dog never dug there again. But I don't know if this would be cruel, or just effective shock tactics?