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Arthritis tends to respond well to some kind of joint traction and maybe some compression with motion. You may also be able to get relief with some kind of scraping tool around the base of the thumb. Are you familiar with Graston or hawk grips? You can get a similar enough stimulus yourself with the handle of a butter knife and some lotion.
Given your job the scapular pain may be related to tight anterior shoulder muscles as well (some of them attach to the front of the scapula and can keep it from gliding in all its planes of motion) make sure you are doing some kind of muscle release for the front of the shoulder along with around the scapula, rib cage and thoracic spine.