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...

Hope this gets resolved for you soon!
I have 4 or 5 other ones in different places that don't hurt or bother me though. I haven't done any injections with mine but if they keep hurting I'm going to have to try something. They're on my right hand & I'm right handed and its getting hard to do basic things.
I had a little lump just in the place you are describing. I think the doc said it was a nodule. I was also having problems with that finger being unable to open fully for a while. He suggested getting a cortisone shot, but I just kept moving the finger and it eventually was fine. The little lump even went away. I have a much larger one on the inside of my elbow, it's very hard, and occasionally tender.
Given the variety of experiences we've all had, maybe you should ask the RA dr., especially since it's so painful for you. It's not a "little thing" if it's causing you a lot of pain!