One of the common symptoms of RA and psoriatic arthritis happens to be chronic fungal infections or candida symptoms. Candida doesn't "cause" RA. The auto-immune disorder causes candida. This can present as fungal skin infections, fingernail and toenail fungal infections, and intolerance to sugar products, dairy, and any other starch or sugar-producing food source.
It may be a very wise option to have labs run to determine inflammation factors and RA factors, particularly during a flare. Some auto-immune disorders that fall under the category of "arthritis" are very, very difficult to diagnose simply because most of them present similar symptoms. It took me almost 5 years to determine what types of auto-immune disorders I had through trial and error and processes of elimination.
Although I understand the hesitancy to consult medical providers, it can be disasterous to attempt self-diagnosis and treatment. If a condition is diagnosed, then moving on to management becomes a series of personal choices and options.