I Have Thumb Pain. I Can't Use My Thumb To

I have thumb pain. I can't use my thumb to push the button on the seat belt to unbuckle. It is very painful to open water bottles or medicine bottles or to grip somethings. It hurts to turn the key to start the car or use a key to unlock the house. It hurts to push on the meaty part of the thumb. Any ideas? I don't text or play games with my thumb.