Your hormones are trying to get back to normal. Any kind of hormonal problems such as mood, weird bleeding or not bleeding at all, headaches, cramps, backaches, hot flashes, etc. the list goes on, should be expected when going off the pill. Your entire body is trying to detox right now, and it's not easy since you were on the pill for a while. Start taking a strong women's formula vitamin every day and drink a ton of water because you have to get your body back into normal mode. And probably it wouldn't be a bad idea to get on some high quality probiotics, too, because that should help you a lot, too.