Re: No surgery!
Exercises will work. Do them twice a day, about 15 minutes, once in the morning and the other before bed.
I don't know why they don't give your son some strong pain medication to give him a break. Doctors don't always listen. I had to almost scream to get some morphine after I had some breakthrough sciatica pain from a ruptured disc. I only took it for a week, but it was a huge help, just to get a break from the pain. Also, meds to help sleep would be good for a few weeks, because sciatica (at least for me) was worst when you lay down and try to sleep. Be sure he has the extra pillows ... does it help to put a pillow between the legs, and bring the hurting leg up toward the chest in bed?
Also, oral steroids could reduce the inflammation. I took prednisone for a week, but I don't know if that is safe for young people.