Do you have a painful base of your thumb? Have you had a change of shape to your thumb / palm? You may have osteoarthritis of the base of the thumb. For more information on osteoarthritis, and information on ways to treat painful thumbs, please see the following link:
Hand exercises for hand osteoarthritis (youtube.com)
For additional information on osteoarthritis and ways to treat painful thumbs, please see the following link to ‘Rebuild’, a blog website by a registered physiotherapist: