What Causes Swelling In The Toes Which Are Sore In A 9 Year Old?

My son who is 9 has painful toe. Started with one red little toe and after a week his middle toes became painful and swollen. After a week I took him to doctor who suggested to contact his orthopedic doctor. He looked at a photo and thought it might be chilblains. He has now had it for 3 weeks. He has lost most of the skin on his little toe.. After week 2 his toes on his other foot have become swollen and red. They are painful to walk on. We have today again been orthopedic consultant. Am now worried as no one seams to know what he has. He is struggling to walk and the more he walks the worse it get.. He has JA and is methotrexate.. 15mg a week.. He is also diagnosed with noonans and has a palumary valve stenosis.. HELP...