Birth control pills can have many side effects. I have never taken the pill you are on but I can say, from experience, that the first BCP I was on made me sick. I now take low hormone pills.

Definitely take a pregnancy test as that is the only real way to determine pregnancy. You should get with your doctor as well and discuss the side effects associated with any pill you plan on taking to avoid confusion like this in the future! Always follow the directions on them!