Hello,
I was diagnosed at 12, I'm now 23 and have relatively low flare ups. The dream was that my RA would go into remission, meaning that it would go into a sort of hibernation until I was 70 or 80 years old. No such luck for me yet.
I was also put on the meth and Humira combo and it worked for 3-4 years. One thing you should know is that since she is so young she may grow a tolerance to it, I'm now on a biologic called Orencia.
PT and chiropractic care will help. The best thing is that she is active when her inflammation levels are low and that she take it easy with stretching when they are elevated. Get her a few pairs of really good tennis shoes, if you go on vacation take into account how long you may be standing or walking. I noticed extreme fatigue during the first 4-5 years after I was diagnosed and still struggle as an adult. I nearly failed 8th grade because I would be so tired I'd tell my mom I was sick so that I could go back to bed.
Another thing you may notice is depression and weightloss. Since I was so young and it took years for me to get diagnosed, I got really depressed and dangerously skinny. I had completely lost my appetite. Research the ways that kids show their depression because it's quite different and more subtle compared to adults.
Research is key, my mom could probably be a rheumatologist. Subscribe to Arthritis Today, keep up on new medications, because believe it or not, sometimes your doctors don't have time to read the newest journals. Humira had just come out when I was diagnosed and my mom brought the medication up to my doctor, he hadn't even studied it yet.
Keep a journal of each day, what she took and when, how she felt; this will help you narrow down what helps and what doesn't, kids can't remember. Research what long term side effects may come with her medications. Research Pleurisy and Pericarditis.
Repetitively teach her to wash her hands, not to put her hands in her mouth, and disinfect her room and bathroom. This will help her a ton when she's an adult and is immuno-compromised.
I'm really sorry that you and your family are going through this. Just know that you yourself will go through a lot of emotional pain as well. Nothing is worse than seeing your daughter suffer the ways that she will. I wish you and your daughter the best of luck.