hi i have a 9 year old son that is having a hard time running.. he plays football and has to run many laps. he is a stiff legged runner and it seems like he struggles to make his strides longer and to also pick up hos feet. When i am helping him stretch before practice i have noticed that he can not straighten his knee or legs with out pain in his knees. He did not have any injury whats so ever to have this causing him this difficulty and pain. He also has adhd,odd, anger aggression, mood disorder and disgraphia. i was wondering if any of that would have any reason for him to be having this problem. i am a very frustrated mother trying to find some answers. please and thank you.