Here are some things you can do:
* Call your vet immediately. They are the best resource to diagnose and treat your puppy's condition.
* Observe your puppy's behavior. Is your puppy limping, holding its leg up, or unable to use its leg? Any change in behavior can be a sign of a problem.
* Keep your puppy calm and comfortable. Avoid handling the injured leg and minimize activity until you can see a vet.
It is extremely important to see a vet as soon as possible. A dislocated shoulder can be very painful for your puppy and requires professional medical attention. Don't delay.