Not into exercise, I get it. But sounds like that might be the cause of weak muscles leading to misaligned posture etc.
One thing for me was that lifting the way I was ?taught ? in school is ineffective and mostly leafy me sore. Good program really just leaves you tired and hungry with little lactic pain. Anyway if you can get him to lift. A good run at squats and deadlifts is like a back reset.
Unless this is a slipped disc or something. Then it?s hard to say what to do.