Hello!
Get an X-ray done and rule out bony injuries and get an MRI to diagnose any soft tissue injuries.
de Quervain's disease is a painful inflammation of a tendon attached to your thumb. You can have pain when you are moving your thumb away from your hand and you can have difficulty with activities requiring a firm grip and twisting of your hand. This pain typically occurs at the base of your thumb and the radial side (same side as the thumb) of your forearm.
If you do not have these symptoms then follow up with an orthopedician for a second opinion and for a proper diagnosis.
Take care!