I am not sure what I can recommend... All I can say is that there was my father who has been having a pretty severe case of Scoliosis, docs said that the only method of treating it is to have a spinal fusion surgery either. They have performed it, my father been on pain meds for a while but then he gradually started to feel better. This has been years ago, now he is all fine (with his scoliosis, as he has other issues now) but anyway. Spinal Fusion Surgery went fine. As I said, I can't recommend you anything and I'm sorry for this, that I can't help, but I just thought about sharing a word of encouragement and say that I'm sorry for your boy to have to get through this. Just stay strong.
All I can do is share our experience my son needed the surgery he had it back in 2010 everything went fine. After a year we seen a improvement in his ability to breath. He was able to sit up straighter and so for us it was a good thing to have done.