Hello, You have been on birth control pills but your period was not bright red but brown thick stringy discharge. Old deoxygenated blood is brown in color. Brown color may be also indicative of old blood in the vaginal secretions. If you have been taking the birth control pills as instructed without missing it then you shouldn t be pregnant. In case you develop early pregnancy like symptoms then you should get pregnancy test done with your first, morning, mid-stream urine to stay on the safer side. Other medical conditions that can cause similar symptoms are ectopic pregnancy, implantation, PID / PCOS, miscarriage (its accompanied with abdominal cramps), hormonal imbalance, ovarian cysts, etc. You are suggested to get clinically examined by a gynecologist, get all required tests and investigations done. You will be managed accordingly. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician