Are you talking about joint pains?
I'm not sure about your child. I started with pains in my feet when I was 7 . It got my legs and hips when I was a teenager. Over the course of 15 years it took over the rest of my body. I was diagnosed at 25 with arthritis and 20 years later with fibro. My nephew was diagnosed at 2 with JRA when he collapsed on us when we were yard saleing. It was 6 months and 18 baby asprin a day before he could walk again. He is now 34.
Another nephew started having severe pains in his legs and feet when he was a teenager. He got a lacross scolarship to college. He was in a lot of pain but he did it. He's now early 30's.
My granddaughter has been showing signs of it with the aching joints since she was 7 and now at the age of 12 she's popping in her neck and shoulders. My Dad said he was about 7 also. Both boys are over 6 feet tall. My grandaughter and I are only 5 feet and Dad came in about 5'6".
Hope things get better