Hi!
You need to pin an object beside your avatar and create two variables that store the previous avatar position.
Then set the following events:
Set object WIDTH to distance(Object_Initial_Pos_X,Object_Initial_Pos_Y,Actual_Pos.X,Actual_Pos.Y)
Set object HEIGHT to Self.Width/15
Set object ANGLE to angle(Object_Initial_Pos_X,Object_Initial_Pos_Y,Actual_Pos.X,Actual_Pos.Y)
System set Object_Initial_Pos_X to Actual_Pos.X
System set Object_Initial_Pos_Y to Actual_Pos.Y
PS.: The Actual_Pos is the actual position of the moving object. I did this to a slice casual game, so I think it will work well with your game.
Good luck!