What Causes Persistent Pain In Back During Periods?

hi, I have a consistent aching in my back. I can t tell if it is my lower back or not. it feels like lower and middle. I have just started my menstural cycle but I usually never get back pain while I have my period. could this just be due to my period or is it my kidneys? I hve no other symptoms but the consistent back pain. I have also had dull sporadic headaches along with it.