You have to seperate the medical condition from the addiction. My son has medical issues and what i've found is that most of the drugs he uses makes his medical condition worse not better even though it is one of his excuses. i can only imagine how cocaine can intensify back pain - especially the next day. If the real problem was the back pain he would be asking to go to a pain management specialist and not self-medicating. Without proper medical care his back pain will get worse no matter how much he uses because its going to take more and more to take the pain away.
You really have to learn to seperate the two. its very hard - i know that when i let my son fall that there is a chance that the reprucsions medically could be fatal but i also know that if i dont let him fall that it will def be fatal for him eventually. so i make a choice - do i take the risk now and let him learn while he is young or do i let him continue knowing that he will certainly die? I've chosen to take the risk now because in the long run its the only chance he has.