If it is a back problem I can relate. Everyone has their own means to recover but he is playing a tough, physical sport. My back was so bad for so long at one point that it hurt to tie my shoes. Every day it was with me, when I walked, lied down, was at the gym. Luckily I was young enough, slightly younger than him and I was able to recover through simple, disciplined actions.
Again, I'm not a pro athlete so this will be a much bigger task for him.
You can tell that he hasn't been himself all season, it was clear really from the first game.