Hi thanks for writing to me
I'm sorry to read that you suffer with arthritis. It really is a terrible thing to have to deal with when being so young. You are not alone though there are about 12,000 children and young people under 16 that suffer with this in the UK.
I think your friends are not very understanding of your condition or how they are making you feel leaving you out of games. They can't be very good friends for doing this. It might be worth though telling them exactly all about your condition and what you can or can't do. Tell them you are not able to run around as they do and it would be nice to play games that you can join in with.
It sounds positive that at last you will be getting medical treatment to help you with this. I'm sure with time and your patience it will work and you will be able to walk and run about more freely.
Can I suggest a website that might help check out www.kidswitharthritis.org this gives a lot of information about coping with arthritis and getting involved in activities with links.
You may want to put a message on the ChildLine message boards and see what other users suggest.
Good luck and take care
Sam