Lately I've been seeing a lot of this. Kids with feet so flat...so collapsed...that they're walking on the SIDE of their shoes, not even on the sole at all. As much as it looks painful for the child to walk, you'd be surprised that the child is probably not feeling much pain. After all, they're the only feet that they've ever known and, while uncomfortable, they're probably feeling this as "normal." The kids would know differently if they were able to try on your feet, but we can't do that yet!
Kids are also very resilient. They are much more flexible and plyable, which makes their feet adapt. You may not even see a child initially complaining about their feet. Instead, look for your kid to not want to walk or run. While shopping, you may find him sitting on the floor when he just can't walk anymore. He also may be tripping a lot when he runs.
When you look at the bottom of your child's shoe, you may see the sole more worn down on the great toe and arch side. In severe cases, you may not even see much wear on the shoe, but rather wear and tearing on the side of the shoe. I've seen kids with feet so flat that they are practically walking on the side of their feet.
Take a look at how your son or daughter walks. If it doesn't look right, it probably isn't! Don't wait for your child to complain. The earlier we can intervene to correct the way your child walks, whether it be with a prefabricated insole, custom orthotic, sports ankle-foot orthotic, or, in extreme cases, foot surgery, the better your child will feel and more active he or she will be for all the years to come.