Hi! My Lower Back Has Been Hurting On And Off

Hi! My lower back has been hurting on and off for month, taking lots od Advil which is unusual for me. In addition my tailbone really hurts. I did not fall and can not think of a reason that would hurt and find it really odd. And, again on and off it can be very painful when I urinate. No fever and otherwise feel good. I am a 49 year old female.