What Causes Cramps On Starting A New Pack Of Birth Control Pills?

I am a 41yr old female. No kids. I was on a birth control with low estrogen which stopped my periods. My gyn changed my Rx because I am a smoker. I have always been a 3 day light no cramps. Since starting the new pills I am having horrible cramps. I am not due to start until next week. One day a week for the last 3 weeks, I have had sudden onset of dizziness, get extremely hot, and have horrible stabbing pains in my lower abd. I thought this may be related to the change of pills, but I am really concerned.