Hello, thanks for using health care magic. Yellow-brown vaginal discharges are not typical of normal vaginal discharges and thus a detail examination is required. It could signify an infection since you have a history of unprotected intercourse. However, it could be just normal due to a slight hormonal disequilibrium and thus pregnancy should be ruled out. Failure of birth control pills is associated with irregular intake, but with one miss and replacement the following day, chances of failure are reduced. It is important to do a vaginal smear test and do a home pregnancy testing in a about two weeks time. Best regards and hope this helps you. Dr. Achuo