Brown discharge is a sign of OLD BLOOD that is being released from the vagina. It's possible that you are experiencing some type of infection, like a yeast infection, and might benefit from a trip to see a gynecologist. Abnormal vaginal bleeding is best diagnosed when it's happening, so try to book an appointment ASAP. AT the least, record the duration, the symptoms, the amount of blood, etc. so that you can present the information to the doctor when you get there.

Yes, brown discharge can come and go. I've experienced quite a bit of it in my early 20's.