I need a idea for a sequel to my first zombie book.. ANY HELP ?

well my first was called TRAPPED and what happens is that a young girl Makaela gets stuck in a small town where they get attacked by zombies and some of her friends and family make it out and the Second book is called IMPRISONED and i need help making a book after ZDAY REMEMBRANCE DAY and thing is.. they get caught in mall the day swine flu injections come out sooo yeah everyone is getting attacked by zombies but i need help soon to start more of my book