Day 7 no period..always been regular (26 days). experienced light brown discharge after intercourse today...what does this mean (old blood or cycle)?

Possibility of preg?: Pregnancy is the most common cause of a missed period. If not pregnant, other causes of a late or missed period include: excessive weight loss or weight gain, increased exercising, emotional stress, having an illness, traveling, medicines (especially birth control pills), hormonal disorders, etc… a visit to one’s ob-gyn doctor is a good idea if symptoms are persistent, recurring, or worrisome.