I feel for your son and your anguish when he's struggling...its a tough thing to watch and not want to hold them close and protect them from the outside world. Yes, I do know what you mean...

Hey...I do have a suggestion tho...and it might not work in his case but who knows..one of my sons also have very flat feet..as in his arches go outwards instead of inwards..A podiatrist recommended orthodic inserts, which helped with the inward rotation of the foot, which affects not only the foot, but the ankle, knee, hip and back alignment...made him feel much less pain when everything was working as it should.

Hope this helps..and give him a hug from me...will ya?