[Coffee.]

Honestly this seems fairly normal. Birth control makes your periods pretty irregular, and this kind of stuff can happen. Really, on the pill, what you are having is called "breakthrough bleeding", it's not really a period, and actually has no medical reason to have it. You can go without it, since you are not ovulating anyway.

There are two things I could see from what you said that could be "causing" this. One, if you went out of the country, your pill taking may have become a bit irregular, and by not taking it at the same time everyday, it made the hormone amount differ a bit more. I really don't think this is doctor necessary, but you do know your own body better than I do. If you would feel more comfortable seeing a doctor and can afford it, it's never a bad idea. But overall, I've had very similar things happen to me.