As you can see Loki is back on his feet. Beth the vet has prescribed 25mg of steroids for 10 days ... I guess this really is a last course of action. Yesterday was hard, heartbreakingly hard. I can only hope for improvement now.
There really can be no definite diagnosis, but it's likely that the piece of spur that has broken off has moved and is putting more or different pressure on the nerve, or maybe another piece has broken off. Alternatively maybe a twist, a stumble or a fall could have caused further inflammation. Truth is we don't really know!