Just seeing this tonight!
Oh no! So sad to hear of this happening to Jackson!
It can come during play, or at rest. Keep him from jumping on and off any bed or furniture, and from using the stairs. His pain/discomfort may help prevent him from overdoing. Now's the time to kick back and relax with him. It can take 2-3 days until he can put weight on it again. Keep him on leash in any situation where he may harm himself from becoming too excited and jumping around too much. He may go off feed due to reduced activity. He should still eat, but maybe not as much. With all his snow play of late, a full body massage would probably feel really good to him, and may help keep him calm.
Congrats to your Dad and Stepmom. Kisses to the Stepmonstasister! Just keepin' it real!
Keep us updated!