Sounds like Lupus to me. My mom has it along with RA. I started to get a tingling sensation on one side of my body and was checked because my mom has it and it turned out to be a neck injury from whiplash but that was bc I started getting the pain on BOTH sides. A diagnostic characteristic of Lupus is pain only on one side of the body. It is a immuno disorder meaning that your body attacks its own tissues - this is why its commonly associated with RA bc they have the same mechanism. This attack of your tissues is most likely what it causing the swelling.

My mom is almost 60 and was diagnosed almost 30 years ago and just takes a pill everyday. She said she used to have to take a lot more meds but technology has gotten so much better that the prognosis is quite better now than 30 yrs ago. The main problems she has are from RA and the actual disfiguration to her fingers and joints from it. But the Lupus doesn't really cause her many problems anymore. Hope I could help!