Preterm back labor?

26 weeks with twins here. I worked yesterday started experiencing some pretty uncomfortable and painful abdominal pain. By the end of the night, I knew I had over worked myself and my abdomen and pelvic area were so sore I could barely walk. I have today off and woke up feeling pretty good. About 2 hours ago as I was laying on the couch, I started getting this stabbing pain in my lower back. It comes in waves but doesn’t last long. I don’t think it’s consistent but when it comes, it only lasts for about 5 seconds but it is pretty intense. I assumed maybe babies were sitting on a nerve so I’ve tried shifting positions and walking and I’m still experiencing the pain. Any ideas? I wouldn’t expect it to be preterm labor but I need some relief