When your arches are off, your feet usually go inward. That makes your skeletal system off. Pain can show up different places. Your ankles can be affected, your knees, your spine, your neck, even your jaw. She might need orthodics. An orthopedic surgeon will check to see if a leg is longer than the other and will check to see if she has flat feet.
Orthodics can make the difference in being energetic or tired, being sore or normal. My dad had flat feet and yet could run all day without his feet hurting. I on the other hand I have to have orthodics. It was a good decision to get them.