Hi, and thanks for your query on eHealth forum!
If the brown discharge came a week or 10 days before your periods, then yes, it can be due to implantation bleed. Wait until your next due date for periods. If you miss periods take a pregnancy test and see.
If the pregnancy test is negative and brown discharge continues, then this can be due to a foreign body (like a condom or tempon left behind) or due to cervical cancer or dysplasia, fibroids in uterus, endometriosis, or due to a STD or fungal infection. You will need pregnancy test, ultrasound, STD panel and PAP smear for confirmed diagnosis. Since a confirmed diagnosis cannot be given on net please consult your gynecologist regarding this. Hope this helps. Take care!