Could you have a combination of juvenile rheumatoid arthritis?

Yes: Jra (also called jia) for juvenille idiopathic arthritis is a disease of unknown etiology. There are many theories for why it happens, many believe there is a virus responsible. The damage to the joints, pain and stiffness is due to an inappropriate immune response which results in the immune system attacking tissues of the host (patient). Symptoms are variable, appropriate DX and rx critical.