Horsegirl, I got my dog from a rescue when he was only a couple of months old and went through this too. I found a stuffed animal at a local pet store that had batteries that made a heartbeat sound and vibration when it was on.

I wish I could remember the name of the company that made it. I will see if I still have the toy. When Seven would get upset, he would lay down on the stuffed animal and the heartbeat seemed to calm him down.

Every dog I've had has gone through what you're experiencing. It's very normal.

Much luck.