Did the vet know he isn't usually crated?? I wonder why the crate, given that he isn't very active as a result of the pain anyhow. I wonder if one of those little fenced-in pens or a quiet gated area would be o.k.?? I always worry that people and animals that are stressed take longer to heal . . . and he doesn't sound happy.
My first dog had a slipped disk and couldn't walk or hold his stool, so it sounds like maybe your little guy may recover??
Hang in there. This must be hard on you two. I'm glad you found a support forum.