Brown discharge! Need Answers !

Erica
My period was extremely late! I don't really have a scheduled cycle. My cycle has been crazy since I went to Korea in 2010 and has never been the same. I was told it could have been stress and it would get back into a normal swing when I returned stateside. I have been back in the 
​U.S. since 2011 and no change. Anyway, since Sunday  I've had a brown discharge instead of the normal. Has anyone experienced this? What could it be?