But Wait, There's More!

I was lucky enough to witness an overtime game yesterday. Here's how it goes down: there's a coin toss, and either the winner or loser decides which direction to kick. Then they go into a fifth 15-minute period, but it's sudden death. If no points are scored during this period, the game goes into double overtime. What happens during double overtime? Can there be a triple, quadruple, quintuple overtime? Does the game continue indefinitely until a point is scored, or do they, at some point, declare a draw?