I have a three year old welsh corgi and yesterday night I came home to find that he wasn't using his back legs properly. He couldn't really stand and cried when I tried to pick him up. Finally at about 5am I took him to the veterinary hospital in our area and was told pretty much the same thing you were. That it sounds like it's a disc problem, we have to do a milogram or something like that to find out for sure, then if it's confirmed it's probably surgery. Now my Poncho is on the Prednisone as of this morning and Tramadol but so far there hasn't been a change. My regular vet is going to call me today about his options and if I find anything else out I'll definitely let you know.