Hi
I think you should talk to a paediatric consultant or a neurologist because this could be something called RSD/CRPS.
It affects your nerves causing you to have Chronic Pain that wont go away. I developed it recently after what I thought was going to "just" be a sprained ankle. There is no specific test that they can do to see if it is RSD they just see if you have the symptoms of it and then if you have more than 3 the chances are you do have it. They may also want to do blood tests to see if you are at risk of developing Athritis.
For me they did an MRI scan, but Im still waiting for the results!!
Hope this helps
Alison