Rheumatoid Arthritis Support Group
Rheumatoid arthritis is a chronic, inflammatory, multisystem, autoimmune disorder. It is a disabling and painful condition which can lead to substantial loss of mobility due to pain and joint destruction. The disease is also systemic in that it often also affects many extra-articular tissues throughout the body including the skin, blood vessels, heart, lungs, and...
http://www.scielo.br/scielo.php?pid=S1808-86942013000200017&script=sci_arttext&tlng=en
If yours comes and goes with flares of your other joints, and not with voice use, it may be cricoarytenoid arthritis as californialynn said. I would think it lasts longer (in line with your other joints) and may get better as you treat your flare up. You should ask your rheumatologist to see ENT or a voice/speech pathologist.
Protecting your larynx from other issues is also important - like controlling allergies and acid reflux - both make that area more sensitive.