In simple terms polyarthritis means pain-swelling in more than 1 joint. In medical-rheumatological jargon we often use this term for inflammatory systemic serious (but fortunately treatable now with new drugs) arthritis of young and middle-aged persons. There are several of these but rheumatoid arthritis is the commonest and requires assessment by a trained RHEUMATOLOGIST (NOT an Orthopaedic surgeon) who would first confirm the diagnosis and then quickly start the latest effective drugs to fully control the disease.
Leaving it untreated or going to alternative systems of medicine or to general physicians or orthopaedic surgeons may delay the disease control causing permanent damage. Remember, it is a medical emergency and time is at premium for protecting joints from permanent damage.