Hi, my period is 3days late. Now I am experiencing lower back pain, which is really hurting me especially when I'm walking. I had a miscarriage in June of this year.I'm also experiencing brown discharge. I'm not sure if I'm pregnant because I had one postive test and three negative tests last month. If it is my period, please can you tell my why my back is hurting me so much. I never experienced lower back pains when I'm on my period. Can it be another miscarriage?