If you missed a period and had sex and 3 days later start bleeding brown blood what could that mean?

Brown flow is light bleeding that is taking it's time to come out of your body so it is turning brown and mixing with your discharge. This may be the start of your period or this may be as heavy as this period is going to be. You can also get this if your cycle is irregular, not menstruation but spotting due to hormonal imbalance. If you go over three months without a period or keep seeing unusual bleeding like this then go see your doctor to find out what's going on.