A rheumatologist is a doctor who completes his four years of medical or osteopathic education followed by three years of residency training in either internal medicine or pediatrics. They are medical practitioners, who deal with the treatment of painful inflammation of muscles and joints, tissues diseases & autoimmune diseases. Several rheumatologists conduct analysis to work out the cause and higher treatments for these disabling and generally fatal diseases. There are more than 100 types of these diseases, including rheumatoid arthritis, osteoarthritis, gout, lupus, back pain, osteoporosis, fibromyalgia and tendonitis. Some of these are very serious diseases that can be even difficult to diagnose and treat.