The basics:

I'm 21, not sexually active, and not on BC.

For the last year or so, I've been having erractic periods as far as timing is concerned. They will be non-existant for like three months, or right on time. I used to be pretty much clock work. So the last time I got it was May.

However once or twice I've gotten a brown discharge, very light hardly noticable, but this week I started to get it again but it's heavier this time around. Not by much though, but enough for liners.

Is something up that I should know about?

This could either be caused by stress or illness, or it could be caused by a hormonal imbalance. The only way to know for sure would be to see your gynecologist. Many women will have irregular period all their life and it can be normal. If the doctor determines that there is nothing actually wrong with you, they may recommend taking birth control to regulate it. Just know that it is not necessary to regulate your period unless it really bothers you.