Lower left side in my back hurts like pins and needles every now and then. If I'm doing something…

Lower left side in my back hurts like pins and needles every now and then. If I'm doing something then sit for a while like I can't relax with out it hurting. And when I'm sitting if I turn or bed sideways I just can't. Its a sharp pain. Started a few months ago. I've Always pretty much had a bad back but not like this. Wonder if it's pregnancy related