Hi there...
I got your PM and came right to this thread.
My parents went to the ER Vet (same as you), got the meds and xrays and told to keep Cole confined. After a a few days, they decided to call the ER Vet and get a referral to a Neuro Specialist (they skipped going to the regular Vet), as the Specialist would give better advice. The specialist did a very good exam and looked at the xrays and said he was fine, not sure what happened really. They weaned him off the meds, and started him on daily Cosiquin and are keeping his jumping to a minimum (just in case).
Please keep me posted on Bella and I will try to help in any way I can. I have to run to a meeting right now, but if you have any questions please let me know?? I did some intense research myself on the topic