A visit to the vet is in order. It is against forum rules to give medical advice, as someone giving the wrong advice could delay a real diagnosis and cause further damage to the dog. It could be nothing but stress, or it could be a blockage, but an internet forum doesn't know because we're not vets. It would be best to call the vet and at least see what they recommend you do. Calls are free.
After you've received a diagnosis, please feel free to come back and discuss in a new thread.
After you've received a diagnosis, please feel free to come back and discuss in a new thread.