Brwon discharge when im supposed to be on period

I have pretty normal periods. The 1st of every month and they are usually pretty heavy. about a week before my period my breasts are very tender. This month I have no tenderness and no cramping. When i started my "Period" it was not blood. It was light/dark brown. For about 5 days. I have had no signs of a period. I woke up yesterday(thursday) morning throwing up and it continued all day. I ran a slight fever during the night but today I am fine. What do you think the brown discharge is? It was not a normal period. THANK YOU ALL FOR YOU HELP!!