I'm sorry.
Ellie is in the same boat and it's not fun. Were xrays done? Are they saying it's likely a disc issue?
If you can't go to a specialist right now, I would suggest at least talking with your regular vet about it. Back injuries like this are incredibly painful. The steroi will hopefully take the inflammation down, but usually pain drugs are given also. A steroid just is usually not enough. Ellie takes a massive dose of Tramadol and Gabapentin as needed.