When the monks were sick and in physical pain way back in the time of the Buddha, the seven factors of enlightenment were used to remind the sick how to cope.

That should be a hint for you to help your son.

1. UNremitting mindfulness. Ask him where is hurts. Ask him to describe the pain in great detail. Ask him to watch the painful areas fro any signs of changing. Can he see the temporary nature of the cessation, moment by moment and day by day.

2. UNremitting investigation of the mental states. Ask him how he likes the pain. Ask him can he learn anything from the pain. Let the pain be his teacher. Ask him can he have a good mental state even if there is pain. Can he be happy and joke around about the pain.

3. UNremitting effort (energy) Ask you son to try to keep up with these teachings. To try hard to not let the pain get him down. The best way to do that is to keep watching for any changes.

4. UNremitting rapture (piti). Ask your son what he likes about the pain. Can he find pleasure in the knowing that he can handle the pain no matter how intense it becomes. Ask him if he can win over the pain, to be master of the pain, and even like it.

5. Unremitting tranquility. Ask your son if he can get the rest he needs regardless of the sensations. can he let the body heal even if it means more pain. Ask him to not run from the pain but to be comfortable with it.

6. Unremitting concentration.  As he progresses in these new practices, ask him to concentrate on the pain to make the pain heal his body. Focus on the healing and keep his mind focused on the healing. do not let the mind wander into despair.

7. UNremitting balance or equanimity. Ask him to use this time to make his mind strong. He can use the pain to concur pain for the rest of his life so that he will never be afraid of pain ever again.