Take a deep breath and don't stress. The pain caused by sleeping incorrectly is usually not serious. If you're a side sleeper, consider placing a pillow between your knees. This can take a lot of stress off your lower back and the upper hips muscles. For people that sleep on their back, I would recommend laying on your back with a pillow behind your knees. This can take some stress off some of the tissues of your lower back as well.