Lower back stretching pain

Hi everybody so I am trying to conceive my second and we have been trying for about four months my next period is due this Monday but last night I started having severe lower back pain feeling like it was stretching from side to side I remember with my first I had this pain and also very sensitive to touch nipples. I don't want to get too excited because it did take us about nine months to try and make my first son what do you guys think when should I take the test!??