are you 100% sure your not pregnant? b/c to me it sounds like you are. just remember pertection is not 100% safe...
Brown discharge is old blood your body is getting rid of. It generally comes at the start of a period, or the tail end. There are a lot of reasons a period might be delayed or skipped, including late ovulation, failure to ovulate, stress, medicines, exercise, diet changes, poor nutrition, rapid weight gain/loss, or a hormonal imbalance. Many doctors are not concerned until you've missed three periods in a row.