Have you taken a test? If you're worried, take a test and see what's up.
If you've been taking your birth control every day, you are fine. The only time I would worry in situations like this is if you missed some pills.
As for the spotting/headaches, these are typical side effects of birth control. Nothing to really worry about. Your best bet, however, would be to just take a test. Most women take the tests just to soothe their fears of possible unwanted pregnancies. So, take the test and you'll know for sure that you're fine.