I Am In Saskatoon Sask. My Adult Son Has ADHD

I am in Saskatoon Sask. My adult son has ADHD to cope with. His current doctor awnts him to remain on Concerta. However he crashes once the time is up. He loses control and now his marriage is on the rocks.
What other medication could he try? He has a Dtr with the same affilcation. His current doctor believes the best medicine is Concerta. We need a psychciatrist