I myself had a similar situation. I basically fostered a 1yr old Sheppard lab mix. Constantly paced and whined as if no one was home with him or sitting right next to him. Tried many things, thunder shirt, leaving the TV on low and leaving for about 15-20 mins and coming right back to give the idea we would be back. I even tried some YouTube videos by searching for relaxation music for dogs. These videos for the most part actually helped. From the trial and errors our situation was a young dog with separation anxiety. Maybe some of these ideas you can try, they may help.