precipitating factors that induce Rheumatoid Arthritis

I am still puzzled as to how at this stage in my life (54)I developed RA.I experienced a few years of a very stressful workplace coupled with repeated throat infections that were thought to be strep but turned out not to be.I then explosively developed RA very suddenly last November.This saw me on sick leave for 6 months,resigning from my Director of Nursing job and wondering what the hell had hit me.Now nearly one year later I am on a cocktail of drugs that I have to say do make a fantastic difference but they are all aimed at settling down the inflamation and stopping my lymphocytes from destroying my exocrine glands.I have completely reevaluated my work, my home life, my housing etc.I am now well controlled and walk 5 kms a day have a reasonably paying low stress job and moving into a lovely house.But still I am tormented as to why my immune system went haywire.No one ever in my family has ever had anything like this.Could it be Epstein Barr that was causing the sore throats and eventually upset my immune system.??? Can I get back to a normal immune system.??