Great. Thanks for the additional information. I really appreciate it.
It does sound like Daisy is dealing with some anxiety. It's actually not uncommon for a dog to develop this kind of behavior as they age.
Some dogs develop destructive behaviors such as breaking through windows, destroying crates, chewing holes in walls and destroying sofas in their frantic efforts to cope with feelings of abandonment. Some other dogs may go on hunger strikes or even begin using the bathroom in the house to cope with their feeling of being alone
Dogs with serious separation anxiety issues may need medication as well as behavior modification help from a professional dog behaviorist. Look for a board-certified veterniary behavorist (ACVB) or certified applied animal behaviorist. As for references from your vet. You need solid guidance from someone properly trained to assist you and your dog.
You might also want to consider using a product made specifically for dogs with anxiety. A couple of these things would be:
Melantonin is an over-the-counter drug that can be used to treat some anxiety issues in dogs and I know that you're already using it in the treats, but sometimes using the actual pills rather than treat infused products works better. The dose you would give would be up to 3 mg given orally whenever necessary up to every 8 hours. More information can be found here: http://www.petplace.com/drug-library/melatonin-melatonex/page1.aspx , which includes risks, warning signs to watch out for and other bits of useful information.
Try a DAP collar instead of the plug-in. These are collars that are impregnated with a man-made version of the dog appeasing pheromone, which is a pheromone that nursing bitches give off to their pups to help them feel calm and secure. It's something that humans can't smell, but it has an amazing effect on dogs with anxiety and other issues. Although you can find them at your vet's office..you can also find them online at places like Amazon.com and Ebay for much cheaper. Just make sure they're DAP brand, as they seem to work better than some other versions.
When I'm working with an anxiety dog, I generally start with the collar, and then add in the melatonin if I don't see a change within a week or so.
You could also look into getting a stronger crate/kennel for her. I work with power breeds and have fallen in love with this crate: https://www.petedge.com/zpetedgemain/catalog/productDetail.jsf?wec-appid=PEDM_WEBSHOP_TR&itemKey=005056A633791ED2B58664B6D06D2FB3&wec-locale=en_US&ceidt=PPCPLA17&WT.mc_id=GoogleNonBranded_Pet%20Supplies%20PLA-NS_Containment&gclid=CN2xyejDicsCFQctaQodrDUC-Q They're sort of like the Alcatraz of dog kennels. If the 100 pound Presa Canario I'm working with can't get out of it or tip it over, I'm sure Daisy can't either.
I hope this helps.