I'm not sure how long the bitch has been like this for, but I wouldn't x-ray unless I were to use Alizin to abort the litter. X-rays during pregnancy have been found to cause birth defects in the puppies as well as predisposing them to higher rates of cancer, and in a breed like flat coats with already a very high cancer risk, you certainly don't want to go putting x-ray through them whilst in utero... See:
https://www.avidog.com/how-badly-do-we-need-to-know/ You'll also need to be very limited in terms of pain medication - meds like metacam and anti-inflammatories can't be given during pregnancy either.
Your first post said that the accident happened 'today' so it really doesn't sound very long at all. Why not give rest a chance and see if things get better that way for a good many days?