I've been getting hand cramps in the palm of my fret hand when playing a particular song where the chords are Em7 to D back and forth over and over again. It seems like it's only when playing that particular song that it happens. I started stretching my fingers out before I played that particular song by putting my strumming hand in between each pair of my fret hand's fingers and stretching them out. If that's clear as mud, I just happen to have my digital camera right next to me...