A urine screening was failed a month ago because Oxazepam was taken. 1 pill, 1 time. Since then, the medicine has not been taken! But a recent urine screening tested positive for it again. Is there any other way it would still be in their system? Is there an OTC drug that may cause it to linger in the system that long? Is there an OTC drug that may prevent it from leaving the system? Is there an OTC medication/food/disease that would cause the false positive?