You're a good mom to be researching for her.
The symptoms you describe sound very much like RSD/CRPS. But just like Ms. Bram just said it's important for it to be correctly diagnosed and if it is RSD/CRPS the sooner it's treated the better, especially since she's young it's more likey to have remission if it's caught early. "Early" is a loose term and I'm not sure if there's an exact defination for that.
A few things are a given. Same as Bram said: The vitamin C, soft warmth, NEVER ICE, avoid cold, slow gentle movement. Movement is ok if it's uncomfortable just not severly painful.
Try to not allow them to do anything invasive or traumitic near the sites of pain until you know for sure what this is.

Some sort of nerve medicine is good too.
Please find her a good pain management Dr. or Neurologist who is familiar with RSD.
It's very good to stay proactive with this. Wishing the best care for her!