One wiper blade isnt working!?

I have a 2003 Nissan Frontier. The drivers side wiper arm isnt moving at all. On closer inspection I noticed that the motor is working and the pivot the blade sits on is spinning when I turn on the wipers, but its not moving the arm. Is something stripped? Do I need a new wiper arm altogether. This is BAD since it's gonna be raining tomorrow and the day after :(