I agree with MrsD on her suggestion to you re: ice applicaton.
I also deal with lower back pain too often, due to disc issues. Ice seems to help so very much! I never put the ice pack directly upon the skin, I place a cloth or thin towel between the ice pack and the skin.

Sometimes heat helps me, but this is rare for me.

When I am done with ice and still having some pain, discomfort, I sleep with an ointment named "Tiger Balm" on only my low back. I use the max strength form of this. (I am allergic to eucalyptus and so many of these balms, ointments, etc, have eucalyptus in them. Tiger Balm is free of eucalyptis, is very warming and comforting. (Just my own experience, of course!)

I am glad your husband is starting physical therapy! This is likely the most helpful approach for him!

Best wishes to you both!
DejaVu