Right before my cousin got married, she was super stressed and forgot to take her birth control for a few days and her period started to start. Not wanting her period on her wedding day or honeymoon, she took all three at once the night before her wedding. From what I understand, she survived. I don't remember her being sick at all from the pills (though, she was getting married, so her nerves were pretty high). I don't remember if it did head off her period (I think it did) and she didn't end up pregnant (to my knowledge, at least).

I agree, drink plenty of water. You could always stop for a week, let your body do it's thing, and then start a new pack in a week. Also, if you still have the directions, they should tell you what to do if something like that happens. Yep, birth control pills come with a nice little packet of directions with an "in case of..." section.