Hello,
I would probably go find a different vet and ask for more help. It doesn’t sound like your vet is helping you enough. I also think that a full patient care conversation is warranted. I talked about how to help manage these guys wrt feeding peeing pooping ambulating and pain meds. I also talk about methocarbamol as I think these guys need this. Also ask about gabapentin and acupuncture.
I have a lot of information on my blog and YouTube channel. Kmdvm.blogspot.Com search Ivdd.
I can’t fathom what this might be, though a toxicity comes to mind. Definitely get her to the vet.