Hello, From your description of the upper abdomen pain, it appears as though your pain is related to the rib cage. This happens in advanced pregnancy as the joints relax and also owing to the pressure exerted by the uterus on the diaphragm and the rib cage. Though, hepatic causes also should be borne in mind. The lower abdomen pain and backache suggest an impending labor, especially in view of your previous history. Please contact your health care provider for necessary help immediately. Take adequate rest, preferably in left lateral position and watch fetal movements. You can use local analgesic for the upper abdomen pain. Wish you safe motherhood.