No period for 2 years, now brown discharge?

I haven’t had my period in almost 2 years since having Nexplanon. I noticed yesterday that my discharge was a little brown, but it happens occasionally so I wasn’t too worried about it. Today though it’s like I’m on my period, but it’s only the brown old blood. It’s not a lot though, I’m not sure what’s going on. I have no cramps or any other “period symptoms”.