its repressed memorys coming to the concious in your dreams...the actual "pain" in your hand did actually once happen, its you body remembering the pain - happens quite a lot to some people, sometimes thats why these wierdos think they are possed my ghosts as they keep thinking someone is grabbing them etc... but all it is - is a memory... now in the dream the mind trys to make a story for this un-known pain (feeling) ..hence the dream, some get the same feelings yet without the dream so it makes a little more sence to them.

Ignore the pictures in your dream and just acept it as a feeling... yep sounds wierd but tis true