Rheumatoid arthritis is a complex condition with auto-immune and inflammatory aspects.

As far as I can see there is no reported evidence that naltrexone is of any benefit to people with rheumatoid arthritis (a PubMed search, "naltrexone" and "arthritis", retrieves 32 papers, two of which suggest that naltrexone may help people with osteoarthritic pain but there is nothing there about rheumatoid arthritis).

People who live with rheumatoid arthritis may benefit from a referral to a specialist rheumatologist who will be able to do a detailed clinical investigation and then, in the light of that, discuss treatment/management options.