A lot of things here. First you can't instantiate a class in that same class constructor because you are entering in an eternal loop.
Second, it's not a good idea to add/remove stage objects from a class except the main game glass. You should add instances of all your movements in the main class for that purpose.
Third, I would suggest you to have all the character's moves in the same movieclip and then gotoAndPlay the right portion of the animation according the keyboard press. It's much more efficient that way reducing the load of adding/removing display objects on each move and let the garbage collector stay in peace for a while