Hello and thanks for trusting me to help you and Snow today. I am a veterinarian with over 25 years experience and would be happy work with you.
It sounds as if what you are describing is possibly a herniated or a ruptured disc her spine. These ca occur acutely as you describe and the symptoms can be anywhere from just pain all the way to loss of feeling and paralysis or anywhere in between. When the spine is irritated by the disc material, it can lead to inflammation of the spine as well as swelling and this swelling if not relieved can lead to permanent and irreversible damage.
Swiftness of treatment is of utmost importance and if there is a chance for recovery, surgery is sometimes needed to relieve pressure on the spine. Definitive diagnosis of the affected disc space can be a challenge and advanced imaging like an MRI is usually needed. Surgery, if performed is best done by a board certified surgeon, preferably experienced in neurosurgery. If is it appearing that may be an option for her, your vet can refer her to someone that with that kind of experience.
Here is a link with much greater explanation about disc disease. LINK HERE
Some dogs with this condition can be successfully managed medically with anti-inflammatory meds and pain meds along with strict cage rest. If the symptoms are not improving over the first 24-48 hours or if they are progressing, surgery is usually the best option.
I hope this is helpful. My goal is to provide you with excellent service – if you feel you have received anything less, please reply back as I am happy to address follow-up questions. Kindly rate me when you are done. Thank you for allowing me to assist you.