Tickle his tummy.
Lay on his back!
It seems your dog doesn't want to be the alpha. She is simply 'surrendering' herself to the other dog.
Scared, or shy. They commonly lay they're ears back as well.
You will have to have treats with you. The dog will see it so direct the treat to the floor and it will lay. After a while you will need to say lay or down while the dog is going down.
If you look at the shape of a dog's body, laying on his back (spine) would be an unstable condition, and he'd roll to the side one way or the other. Dogs do not lie on their spine because it hurts. :) There are dogs that lay right on their backs, my dog does it.(Jack Russell)
Dogs are mammals, they do not lay eggs...
If your dog is still under the bush it is my dog lay under the bush but if he's not under it still it's my dog laid under the bush.
Dogs may choose to lay behind your back because it provides them with a sense of security and protection. This position allows them to keep an eye on their surroundings while also feeling close to you.
No, they cannot.
The dog laid on the floor.
A dog may lay flat on its stomach to show submission, relaxation, or to cool off on a hot surface.
It's obvious the dog is in pain. Take the dog back to the vets and if they do nothing get a second opinion! Ask the vet for some painkillers. Also lay on the carpet with your dog and gently stroke them to calm them down. Get to that vets ASAP!