I have the same answer for doing DIY medical treatments –don't go there.
@TLS Guy said the same thing, only he doesn't suffer fools as well as I can (sometimes
).
You have rheumatoid arthritis (RA). My sympathies. It is a serious and painful auto-immune disease. And it needs proper treatment.
You have also seen a physician about RA. Is that a board certified rheumatologist? In the last 20-30 years there has been significant development of new & effective treatments for RA as well as other auto-immune diseases. Some are injected monoclonal antibodies that are expensive. At least one of them, Humira, has recently come off of patent protection and several less expensive generic substitutes are now available in the USA. They have been well tested and they are safe & effective. They've been used for years in Europe and the UK. None of these treatments cure RA, but they can relieve it's most serious symptoms. Ignore them at your own risk!
Finally, about that so-called paper you mentioned about earthing. It's garbage. Just don't go there! No one knows what causes auto-immune diseases. But I absolutely guarantee you that is has nothing to do with ungrounded electricity, stray electromagnetic radiation, or anything else like that. I could go on and on about what garbage that paper is, but I'll stop here.