I Need help. my dog is really poorly

Hi, I have a minature wired haired daschund, she is 5 years old and has never had any health problems untill now. She is very active and lively and last Saturday the 22nd August I noticed that she went out into the back garden to do her business and she couldn´t jump back in the door. I called her and showed her treats which she would normally run for but she just could not get up the step. Then we noticed she could not get up the stairs to go to bed and normally she would have no problems climbing the stairs so we had to carry her up. I took her to my local Vets The Veterinary Clinic in Castle Bromwich on the Tuesday 25th because I could not get her in on the Monday and I was informed that she had a twisted her back funny and it had caused an inflamed trapped nerve in her spine. She was given a Valium injection to stop the muscle spasm she was having and they also gave her an injection of Metacam for pain relief and to take down the inflammation of the trapped nerve. I had to take her back the following day on the Wednesday to be checked over and to see her progress and to have another injection of the Metacam. Her condition had improved a lot however she wa still not right, the vets gave me a course of the Metacam to bring home and continue to give her for a week, she is booked in for Wednesday 2nd to see the vet again. I thought she was starting to get a bit better however today Saturday 30th she has got worse, she is still ok in herself but when she walks she is dragging her back legs behind her, it´s like the back half of her is not functioning properly, she is still able to go to the toilet but she is clearly finding it difficult. Have you ever heard anything like this before, if so could you advise on what you think it could be. I would appricaite it if someone will talk to me and get back to me as soon as. Thanks, Katie.