Hi
Welcome to the forum!
If there is arthritis and the doctor suspects that there is a viral infection in the body, the use of prednisone will be restricted. The steroids reduce the immunity in the body. This lowered immunity can cause an existing infection to flare up. Hence your doctors are restricting the steroid, which will help with arthritis. The RA factor decreasing could be because of reduction of symptoms or because there is no flare up.
The virus affects people either with rheumatoid arthritis or infectious mononucleosis. The virus can be a parvovirus, Hepatitis A, B &/ or C virus, alpha virus, rubella virus, HIV virus, EBV, echo virus, coxsackie virus, or any other virus.
Treatment is generally by analgesics and nonsteroidal anti inflammatory drugs. Sometimes an antiviral therapy is given. If Hepatitis virus and HIV virus are detected they need to be treated in that line.
However without examining it is difficult to give a confirmed diagnosis and treatment on net. Hence consult your doctor and discuss these points. Hope this helps. Take care!