What has Roger Chillingworth been doing?

After arriving at Boston and finding his wife in utter disgrace upon the pillory, he chooses to stay and live in the city. His uncommon intelligence and skill as a physician soon make him quite popular. Dimmesdale's poor health and Chillingworth's interest in the young man combine to make many of the church officials try to get them to live together. Dimmesdale declines at first, saying, "I need no medicine."