Urgent Help Needed

My baby budgies just got out of the box last week. I got them out of the cage to check on them and one of them jumped a big jump. So i put it back in the cage. This morning it looked as if the back is arched and he is now the only one out of the box. Did i break it or there is hope? Maybe if i gave them calcium??!. I can't go to the vet right now because of the lockdown. I am going tomorrow but if someone could help me.