I sympathise - with you and your husband.
My late partner had dreadful sciatica - surgery was never an option.
It's draining for both of you.
I bought, from Amazon, a couple of those heat-pads that you can 'velcro' on to the lower back - either heated up via microwaving, or chilled in the freezer for a while. They certainly helped, quite a lot in fact.
He also found a tens machine helped.
Are they going to offer him nerve-blocking injections?
I understand how you feel, having to watch someone suffer and be part of their care, is very isolating.
Have you tried any online support groups? It really helps to talk to other people in the same situation...