Hi V.,
When I was twelve, I too was diagnosed with JRA after about a year of not knowing what was going on with me. Mine started in the right knee and eventually spread to all of my joints. I went back and forth from orthopedics to rheumitology until they finally diagnosed me. It was frustrating. I received the best care from CHOC.
I am now 38 and have been in remission since I became pregnant with my son at 28. One of my doctors said that can happen although they were not sure why. Happily this seems to be an illness that can be outgrown so thank your lucky stars for that.
Your son will probably be quite fatigued and medicines will only add to that. It is important to stress to others that he really does have an illness. I was hurt by so many that did not believe me because I did not look like their was something wrong with me. My grandfather years later apologized to me when HE got arthritis, saying he didn't realize when he was telling me to "tough it out" how much it really hurt.
Be your son's biggest advocate. My mom was mine. I would let him be the determining factor on how much activity he has, with the doctor's input of course.
Good luck to both of you. Please don't be discourage because in all likely hood this will eventually go away. It could be soo much worse than arthritis. Keep telling yourself that on the bad days!