Brown vaginal discharge for 6 days?

My last period was on 6/11/11 and I'm not due for my next one until 7/9/11. I have had brown discharge in between periods before but the past 6 days I have been having an abnormal amount. I have referred to it as a "brown period". It's beginning to worry me now. It's just way too much discharge to be having for this long. Also, if it helps, I have not been sexually active since the beginning of May and I have had 2 completely normal periods since then. So I don't believe pregnancy could be the issue.