2. Temperature
In the case of autoimmune conditions like rheumatoid arthritis, the swelling and pain are actually caused by the patient’s own body turning on itself. This is the same thing that happens during an allergic reaction.
And in fact, it’s also why we feel unwell when we have an infection: the symptoms aren’t caused by the infection itself, but by the body, as it attempts to drive out said infection.
Thus you may feel as though you have the flu or a cold during this kind of arthritis and with that comes a high temperature, sweating, and the rest!