Hi and welcome to KickAs! I am sorry to hear about your son. You will all have a lot to take in as you learn more about how this disease will affect your son. It sounds like your off to a good start with your visits to a Children's Hospital.
I have AS and my oldest daughter is being followed at our Children's Hospital. She has SI, hip and chest pain. She has tested positive for HLA B27. She takes Tylenol Arthritis as needed and uses a hot water bottle when she is sore. I have also spoken with her school and she is able to get up and leave the class when ever she needs to. This could be to take meds or to walk and relieve any stiff joints. The school has also given her extra copies of her school books so she does not have to strain herself on her long walk home. My daughter is in high school. Lauren has recently started a wheat free diet. She felt more pain this summer when she was away from home for a summer job. When she came home she was eating healthier and noticed her symptoms did improve. This would be easier to try than a starch free diet and might provide some reliefe. I think that people are more inclind to follow a diet when things like pain level are clearly affected.
Try and be positive around your son and encourage your child to enjoy life and be active. Lauren enjoys gym class and we encourage her to "move it not loose it"... There are so many new meds being developed to help people with AS. I think that your sons quality of life will be much better than people who have not access to some of these recent meds.
There are other parents here who have children with AS - I hope some will find your post and give you some more help.
Take care,
Beth