
As suggested a cage might help (or at least protect her from doing any damage to herself!) They are not cruel, I have 4 dogs and a cage big enough just about for 2 to curl up in and its a rush to who gets the cage! Another cage is where two girls sleep, as soon as we have to go out for more then 2 hours they go in the cage and they rush in (they have to go in due to chewing up stairs when left whihc is a pain for us a possibly dangerous to them)
She obvously isn't botherd about being shut away when she knows your away, maybe she's worried once you've left you won't come back? Try taking it bit at a time, walking out the door, shutting it and walking down the road for a minuet, then come back so she knows your back.
If you do decide on a cage then get her used to this, while your at home let her go in at will leaving the door open, when she goes in, shut the door for awhile.
At the end of the day a cage is just another form of dog bed, when left open they are not shut in. Infact I have found dogs will prefere this as many when asleep would rather a confined area where theres less area to watch incase they get attacked.
A good place to pick them up is ebay but also from pet shops, dog shows, and I'm sure you could find plently on "online stores" you could order off of.
Good luck