What can cause back pain that moves around? yesterday, it started in my upper back, near the shoulder blades. now today, its moved to my left side and my lower back. my period is in a week, could that be involved?

I wouldn't tie in upper back discomfort with your menstrual cycle. Did you strain your back, sleep in an awkward position,have a poor mattress,were in a draft? Is the back discomfort worse with motions of the spine? If the discomfort is not severe,I would give it several days of relative rest & take advil as needed to see if it resolves as most musculoskeletal causes of back pain do.