3wks ago, i injured my thumb (sat on by someone while bent). still painful at the joint. could it be broken? if so, would treatment just be a splint?

Need exam: A splint might help but a soft tissue injury is usually improving by 3 weeks. If it still hurts, i would recommend an examination and possible diagnostic imaging to evaluate a possible underlying bone or ligament injury that may require more treatment than just a splint.

Thumb ligament: A common injury to the mcp joint an ulnar or radial collateral ligament. While splinting may be used for some of these others with a complete rupture can need surgery and often do better if that surgery is offered earlier.