What Does Headache And Spotting Between Periods Indicate?

Hi there, I am 22 and am on the pill and have been for over 4 years . I started my period on the 14th and finished on the 18th. It is now the 21st and the last few days i have been experiencing headaches which is uncommon. Yesterday i starting spotting and along with that came cramps, it's seemed to have stopped about lunchtime today. I was wondering if anyone could give me some advice about this. Nothing like this has ever happened to me before.

Thanks