Yes, they make kid sized knee braces. Check your local drugstore! Also, get better shoes if you intend to walk/run again. And work on strengthening your leg muscles too, this will help your knees. You don't need to go to a gym even, there are things you can do with light weights or ankle weights. You might have to accept that running isn't the best for you. I have some knee trouble, and I know I'll never run more than 12-15 miles per week if I want to keep my knees relatively healthy. And I sometimes have to ice them and take ibuprofen. it sucks. But I like to run for exercise so I do it in moderation. Anyways, yes--bad shoes=bad for knees.