Crate rest and antiinflammatories asap, liver support for the anti-inflammatories. I might alo bathe the joints in something like hyaluronic acid (joint supplement), or adequan (canada and other non-US places use a different injectible product, cartrophen vet).
Since there was a trigger event, I might hope that getting the inflammation down would help.
I personally would get to a certified chiroparctor asap (www.avcadoctors.com
, not a VOM vet that might say they do chiro but down't). I prefer the chiros that are also chiros for humans, but they all receive significant training and upon examination will be able to tell you if chiro is appropriate for your dog's current situation. My dog's chiro has rehabbed a number of dogs that could not walk.
There is a spinal stroke called an FCE, and sometimes the dog will recover slowly over time, though acupuncture is a huge help there.
I am o very sorry, this is a terrible position to be in.