you are suffering from could be due to either stretching of the back muscles as a result of increased abdominal size or lordosis
or priming of the cervix
. You may apply some local analgesic
applications and hot fomentation, if needed. You may also take a pain killer after consulting your doctor. Try sleeping in the lateral, preferably in the left lateral position, with a soft pillow underneath your side. Please be patient, it is going to be only a few days more. Wish you a safe delivery.