I'm am experiencing brown discharge a week before period is due it's odorless and i'm not on birth control is it normal?

Not normal, get care: Any new or unexplained vaginal discharge needs professional evaluation. Colored discharge (yellow, green, tan, brown) often means infection. In sexually active women, STDs like chlamydia, gonorrhea, or trichomonas are frequent causes, although gonorrhea and chlamydia are uncommon at your age (30). In any case, see your doctor and take it from there. Good luck!