I'm 20 years old and the past 3-4 days, i have been having brown with red, odorless discharge. i've been on the depo birth control shot for a year.

Brown discharge: "Depo shots" are long acting progesterone, which can suppress ovulation, but not always. If you did ovulate while still using shots of "depo-progesterone" for contraception, you will still be "protected" but bleeding will occur just like a "period". If you are late getting the shot, you might still become pregnant, so get a serum HCG test to be certain in a couple weeks.