Side effects of stopping the pill

So I was on the pill for a little over a year. I finished my last pack at the beginning of May and I got my period then. I wasn't expecting my period for the first days of June but I got it again on May 22nd. I got my period yesterday but I had terrible cramps and it is really light flow. For weeks I've experienced terrible headaches and mood swings and very emotional, has this happened to anyone before? How long did this last?