Thank you for the additional information.
Breaks in the bone
are often very painful and dogs will usually cry out or try to withdraw the affected leg away from you when you touch it. However, Some dogs are more stoic than others. It is still possible that the leg is broken. There can also be a hairline fracture, rather than an overt break in the bone. Often times x-rays of the leg are necessary to definitively diagnose a fracture.
This may very well be soft tissue trauma to the leg such as a ligament injury. Some ligament injuries may take a couple to a few weeks to heal. These are often not visualize on x-ray, the x-ray may simply show evidence of inflammation.
Since it just happened, it may be a good idea to cage rest him for a few days. Only allowing him leash walks outside to go to the bathroom, otherwise he should be confined. This will allow him to rest the leg for optimal healing. You can ice the leg, the swollen area, several times tonight for 10 minutes at a time. This should help reduce or minimize the swelling. He may also need some pain medications. It is best to have your veterinarian prescribe dog specific pain medications as they are often safer and have less side effects. If you cannot get to a vet A published dose of Buffered Aspirin is 5 mg per pound of body weight every 12-24 hours. This drug should not be used if your dog has health issues such as kidney disease, liver disease, or bleeding
disorder. Please let your veterinarian know that you if you have given your dog Aspirin. This drug cannot be given with other drugs your veterinarian may want to use for pain control.
I recommend trying the cage resting and ice and monitor for improvement before trying the Aspirin.
Good luck. Please let me know if you have any other questions or concerns.