I just read through this entire thread and I would now like to put my 2 cents into this as well. After looking at the pictures, the steroids not working, the legs, the crying, I have to say that TEAGAN comes to my mind! At first we thought it was a disk in his spine then AAI but actually it turned out to be the ligament was severed in his neck from his injury. Look at these pictures and video.......
http://www.yorkietalk.com/forums/sic...old-puppy.html
When he was xrayed it did not show the injury and it was not discovered until he was actually in surgery for a possible AAI repair. I wonder if it is possible this is what happened in the fall?
YTNR has Teagan now and after surgery he made a full recovery. I could find out who the surgeon was that did his surgery if you would like.