help ?

hey ladies! so I posted on this a few weeks ago, but got no responses so I figured I'd try once more. so a few weeks ago, I stopped taking my birth control. about a week or so ago, I'd started taking it again, but at inconsistant times during the day (irresponsible I know, but we all get caught up sometimes). so about 3 days ago, i started taking it at the same time every day. well today, I started to get really bad cramps and backaches (similar to the ones I get when my period arrives) so I went to the ladies room and saw that I had a moderate amount of bleeding (even though I still have about 16 days until my period is predicted to start) so I plugged it up and went about my day. however, I noticed that a few hours later, the bleeding had stopped. this has been happening the last 3 days, almost the exact same scenario. can anyone explain what's going on?