Hello,
You had some 
injury in your thumb while working. You are now experiencing pain, a bump on the thumb that is not movable. You have discomfort with your thumb. It looks like you have ruptured ligament that is forming a lump (bump) or swelling. Tenderness, 
bruise or discomfort in the thumb may cause the thumb to feel loose and unstable. It may cause difficulty in doing the daily schedules or work.
You are suggested to get clinically examined by an Orthopedics, get X-ray, MRI done to detect any rupture in the tendons or ligament. You will be treated accordingly. If you have 
thumb tendonitis you will have difficulty in grasping anything. Thumb weakness or 
stiffness causing difficulty in picking up a glass/ coffee mug, Swelling or bumps in the thumb are also symptoms of tendonitis. In the meantime, you can take 
acetaminophen, one stat when pain. Avoid straining the thumb. Get treated at the earliest.
Take care. Hope I have answered your question. Let me know if I can assist you further.
Regards,
Dr. Nupur K., General & Family Physician