Nexplanon HELP!

Hey ladies, so in August of 2016 I got the Nexplanon inserted and had a final period that lasted about 5 days. (Nexplanon is good for 3 years) I haven’t had a period since then. However about a month ago, I started having brown discharge and then actually bled fresh blood about two weeks into this random bleeding cycle. It’s been off an on but now the brown discharge is getting worse and has a horrible smell to it. I have an appointment with my gyn on Friday but I need to get opinions. Is my birth control failing? I am sexually actively so could I be pregnant? (I know this is a dumb question because generally having a period means you aren’t pregnant, but I don’t know what the brown discharge means.) Also, has anyone had Nexplanon fail on them? And if so, what are the signs it’s no longer working. Please help me with this, it’s been stressing me out so much lately. Thank you! ❤️