The top knuckle on my right thumb is swollen and painful.there is a bb sized lump on the left side of the knuckle.i can't bend my thumb.this seems to happen when i am doing carpentry and using my hand

Inflammation: Something causing inflammation of that joint. It may be gout, infection or simple traumatic arthritis if that joint. Best to be evaluated, have some blood tests, and may be an x ray as well. Until you see a doctor, avoid trauma (carpentery(, take aleve (naproxen) 3 times a day.

Osteoarthritis.: The lump you describe is probably a node which commonly occurs at the joints of the hand digits as a result of osteoarthritis. If it occurs at the joint adjacent to the fingernail, it's called a heberden's node; if it involves the middle joint, it's termed a bouchard's node; the one you have has not been given an eponym.