I've been on the pill for about 4 years now, and my periods have been getting shorter and shorter since I started to take them. I just started a new year of pill packs two weeks ago, right after my last period. I'm having pain (almost like period pain, but not nearly as intense) occasionally on both sides. What could this mean? I have not missed a pill in three months or so, and I last had sex 4 days before my period. We did not use a condom, but the pull-out method (which I KNOW is not too effective).