Is it normal if my muscle underneath my thumb moves? Also, the bone underneath my thumb has been hurting. Any answers?

Thumb pain is common. Thumb problems can be simple or complex. the joint at the base of the thumb is known as a saddle joint. The joint at the base of the thumb is commonly afflicted with arthritis at advanced ages. This sometimes responds to oral pain relievers but may require a corticosteroid injection for temporary relief. Surgery is needed for severe unrelenting pain. I hope this helps!