Hi I've Been Using The Implanon For The Past 4.5

Hi
I've been using the implanon for the past 4.5 years. During this time I've had no real issues apart from a year ago when I had a massive heavy never before period with blood clots lasting for a day. I've had nothing since, I've had a Pap smear and an ultra sound which were fine and healthy. Recently in the past 3 months I've been sexually active and have a partner. All has been well apart from the last few months, just for a week now I've had this very light brown discharge. I'm not sure if it's normal or whether my body is going through a change. Should I be concerned or is this just a side effect?