On my left hand, on the palm side, near the base of the thumb, in the joint, I have a knot about the size of a marble. It came about recently when I was lifting a bit more weight than I should have attempted.
The odd thing is that the lump is tender, but I don't notice it otherwise. It's relatively hard, about the density of a rubber eraser. I can still lift as much if not more weight and it doesn't bother me in the least. Is this something I should be concerend about? I looked on the web for answers to no avail.