hello ur periods were late by 4 days & then u had light brown discharge. ur previous menstrual cycles were regular normal flow first of all u need to rule out pregnancy for this u should repeat upt after 5 to 7 days after previous upt with first morning urine sample other alternative to rule out pregnancy r blood test ( bhcg) if ur repeat upt comes weakly positive ( test line lighter than control line ) u should visit ur gynaecologist to rule out ectopic pregnancy ( bhcg & ultrasound may be needed )which can also cause spotting after delayed periods if ur repeat upt is also negative it means u r not pregnant brown discharge could be due to premenstrual spotting. u will need to visit gynaecologist who will prescribe u medicines for periods to come delay in getting periods besides pregnancy can be due to stress , thyroid disease, hyperprolactinemia, polycystic ovarian disease also soreness of breasts & backache can be due to early pregnancy but they can happen in other situations also so pregnancy cannot be diagnosed on the basis of these symptoms alone hope this helps you