Sorry to here. My niece went through this. Feel so bad for any kiddos that get hit by it. Anyhow, just eating a low inflammatory diet.... no sugar and refined grains, excess bad oils, ect.... is really a great start, and thats what Primal is. A couple things that maybe could help you along would be getting plenty of bone broth (2-4 cups a day)... this has lots of great constituents for joint health. Here is a link: The Jade Institute | Bone Broth for Health Building: Nourishing the Liver and Kidneys. The other thing would be to become a huge fan of spices like tumeric and here is a link on that Top 10 Favorite Herbs and Spices | Mark's Daily Apple.
3 years "low carb" Primal.
Dietary hierarchy is: Fatty and gelatinous meat/eggs/seafood/offal > raw and fermented dairy > nuts and seeds > fruit > starch > veggies > everything else.
Backyard permaculture, gardening, and fermentation as healthy hobbies. Lift heavy stuff and move a lot.