Blood spotting and brown discharge for 5 days in the middle of my cycle. What might it be?

It's probably normal. Menstrual cycles vary from woman to woman. Around the time of ovulation, at midcycle, hormone levels are fluctuating greatly. It is not unusual to have some spotting at this time as a result. It doesn't necessarily mean anything is wrong. Skipping cycles for 2 months or more or heavy irregular bleeding require an evaluation.