My 5 year old has been just diagnosed with juvenille rheumatoid arthritis?

My 5 year old since birth has had so many issues! He will be 6 next month in in his 6 years he had 1 surgery for pyloric stenosis, been in chronic abdominal pain, has lazy bowel disorder, hearing issues, severe GERD and damage to his asophagus! Just the last 3 -4 months he has been complaining of legs and foot pain where he cant even walk! 3 days ago he broke out into what look like hives from head to toe but they are not itchy! I took him to the hospital and they mentioned this and to take him to his pediatrician! I did so today, they did blood work and the doctor diagnosed him with juvenille rheumatoid arthritis! I do not know what to do and I am asking for the help of the answers community! I hate seeing him in pain and not being able to move and now he has this rash EVERYWHERE!!! How can I help him in daily activities,etc and he is huge into sports, do I need to make different arrangements for this as I dont want to make anything worse! What can I do to lower the symptoms if anything? Thanks everyone in advance!