I have the implanon and have had it for about 3 years now. I'm 19. Before I got the implanon I was on my period for about a year straight after I got it I stayed on my period for about 4 months and hadn't had a period since. Now the period has started back and I have been on it for about 4 months. Could this be a sign of cervical cancer?

I don't think that's cervical cancer- more like hormonal imbalance. Either way, you should see a doctor.