Your body produces hormones during pregnancy that aid in the lubrication and softening of the ligaments and joints in your pelvis. Whether or not you are pregnant, stress can cause back pain. Stress makes muscles tighter and more painful, especially where there is weakness. The growing weight of your baby must also be supported by your back, which may put strain on the muscles.You can have hot towel compress in order to sooth the pain. A basic exercise only as per the consultation from your doctor will also be helping in soothing the back pain. Relax take good and diet and good rest will surely help. Also try sleeping on your side, not your back.