Constant lower back pain, no obvious cause.

Patient: For the past couple weeks I have suffered from constant lower back pain, on the left side but occasionally it will move to the right side I’ve had to take up to 6 paracetamol a day! To no avail, the pain just won’t shift! At first I thought it might be my period causing it but the pain started before my period and continues long after it has finished!!I don’t want to go to the doctor just yet as I don’t have anything else ‘wrong’ with me, it’s just my back.I’ve never had any problems with my back and the pain seemed to come on very suddenly.Is this something I should be concerned about or will it just pass eventually?