i 16 years of age and have been on birth control pills for almost two years. i have experienced a moderately thick light brown discharge which seemed to be old blood, it was a very small amount and then a day or so later it came again and was a very small amount once again. since then, there hasn't been any signs of it. this discharge happened shortly after i had symptoms of a yeast infection (that went away within a few days). my period is due next week on tuesday and i have no idea why this brown discharge/ old blood could have appeared.