Dark brown discharge, headaches, period due soon. feels like i'm on it. pregnancy?

You may be having: an early period. Reasons for irregularity include weight gain or loss, breastfeeding, alcohol use, eating disorders, marked emotional stress, endometriosis, uterine fibroids, cervical polyps, polycystic ovarian syndrome, excessive exercise & pregnancy. For severe abdominal pain or hemorhaging - seek medical care.

Can't tell: Wait for a week after you miss your period and perform home pregnancy test