Dogs on the whole are sensible - if it hurts to move, they'll stay still, and rest is usually the best thing for them. Is DJ happy in a crate? Because really that's the only way you can keep them quiet - perhaps with a kong to stave off boredom, and moving the crate around so that he can be with you in the living room and elsewhere. A buggy helps too, so that you can take him out and about and he can watch the world go by and meet people, and gradually take him out of it for a few minutes' walk as his back improves. My Oliver has mild spondylosis (bang on top of his syrinx!) and when he has his very occasional flare-ups, the crate and buggy regime works well to keep him quiet but also stave off boredom. Mind you, he's one of the most laid-back Cavaliers I've ever met and takes everything in his stride!
Glad DJ is improving,
Kate, Oliver and Aled