I was hitting 2 hammers together and saw small sparks.bleeding from a pen hole in my wrist.by or near a vein 3 days later still swollenand verypainful

Pen hole?: Uncertain of the explanation of your problem but perhaps some of the iron from the hammer heads chipped off and went into your wrist. A simple x-ray would visualize any foreign object made of metal that is lodged in there likely causing the pain and swelling. A visit to an urgent care for an x-ray could help.

Whoa!: It sounds like you whacked a splinter of metal into your skin! If it is holding a pinhole in the skin large enough to keep bleeding, that is highly irregular! Make your way to your Family Doc for an evaluation. He may need to take an x-ray or refer you to a surgeon to figure out location and an approach to bringing this foreign-body-removal issue to a conclusion!