I had a very similar situation with my dog, she wouldn't bark but whine something aweful and chew things, or even get sick at times. Mine was abused and when we got her to finially trust us she suffered from severe separation anxiety, so bad in fact that during our wedding we had to leave and pick her up from the kennel, she had started vomitting and had really bad runs, so right after the cermony we had to go and get her, she stayed under our table all through out the reception. Anyway, crate training is a good way to do it for some dogs, it helps to make them feel safer but for others it might make the situation worse. For us the crate didn't work (I think it had something to do with the abuse she suffered). For us we started taking her with us when we could and left her tied outside the store (where we could still see her, but she couldn't see us), that actually helpped a lot. The other thing we did was to determine a "safe zone" in the house for her, we put her bed beside our bed in the bedroom and had all her toys there (this is actually a modification of crate training) and when we would leave the house we would put her in the "safe zone" and make her stay there, and then leave the house. She was, and still is, overly excited when we would come home, but the whining and chewing stopped. It took about 6 months for her to be relatively cured of it, she still suffers some, we cannot board her we have to get someone to come into our house to stay with her if we go on vaccation but the day-to-day leaving the house is no longer a problem.