My Monthly Started Yesterday Afternoon, But I Have Had Severe

My monthly started yesterday afternoon, but I have had severe back pain the last few days. Today it has been so bad it is almost unbearable to walk, sit or lay down (with tylenol). Should I go in to see a doctor tonight or wait a few days to see if it goes away? If I wait, I won't be able to go to work as it may be too strenuous of work. I'm not sure what to do.