Why is my discharge brown?

First off, I know this isn't just spotting. At first I thought it was because I forgot to take my birth control pill until around 1pm (when I usually take it around 9am or 10am) for a couple of days. After doing this for a couple days I my discharge got darker and it just looked like spotting.. it was that same consistency and everything.  I didn't see any color yesterday. Then today I just went to go pee and my actual discharge was brown. Like pure brown, like not a deep brown or a reddish brown.  Discharge is pretty normal for me... but this was really weird.  There is an odor but I don't really know how I would describe it.  Also, I am sexually active. I tried just googling this first to see what I came up with.. but I'm still confused and worried. Please help :/

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