Re: What does this mean?
This could in fact be from the birth control. The more of anything you put in your body the more your body reacts to it. Sometimes your body grows an immunity to it, other times a side effect. Also to conisder, there is a lot of bloating that happens when your period comes around.. something as simple as sleeping on your side, or with your leg twisted funny can cause pressure oversight on a muscle or internal organs. Thus intern the body part with pressure on it now becomes inflamed itself causing you more pain.
I sugguest, not being a doctor, to try a basic tylanol or advil and a heating pad over the next week. If the problem worsens or continues see your doctor right away.