What could cause wollen joints, and calluses/bumps on fingers?

Many possibilities: Joint swelling is a sign of inflammation. If chronic , it can be related to a systemic cause such as autoimmune disorders (lupus), or age-related degenerative cause (osteoarthritis). If is is self-limited, a minor injury may be the cause. Calluses are caused by chronic pressure. "bumps" could be anything but may indicate chronic joint disease. See your physician for evaluation.

Arthritis: Arthritis in some form is a common cause. The bumps on the distal joints near the nails are called hebreden's nodes and the ones near the pip or middle joints, bouchard's nodes.