Dislocated?
dislocation or a subluxation or a disarticulation
The joint has been dislocated.
a tail bone
it may be at weird angle if they broke it and if you feel the tail you will feel a lump or a gap
Try an osteopath and physiotherapist
The bone that supports the tail feather bone is the scrodum or the dick
The generic term for a bone that is displaced at the joint is "luxated". A partially dislocated joint may be called subluxated.
The bone in a horse's tail is called the Dock. It goes from the top of the tail, to about mid-tail or shorter.
That is the tail bone.
bone
tail bone