When you say raunches up, do you mean her back was arched? If so, that was the first sign that something was radically wrong with Lyla. She stood with her back arched like a cat. This is all so clear in my mind so I can only tell you what we were told, whilst meningitis is possible, it is rare and any spinal specialist will almost certainly discount it after an exam. If it is a disc, speed is of the essence as the longer you leave the cord to bruise, the more damage may be done. The vets advised the same as yours (after a conversation with a specialist), an overnight rest but when it was clear that didn't work, she was down to the clinic and operated on next day. I have no idea of the last thing but try to stay positive. A good vet should be able to pinpoint the part if spine affected by exam and John Ferguson knew at once when he felt her back.
It is very scary and my heart goes out to you both. If I can be of any help then please just ask xx