prolonged period after nexaplanon

I'm almost 17 and just a got the nexaplanon (arm implant) birth control and I got what I thought was my period like a week later but it was different. like a dark brown and but pretty light. light enough that there would be no discharge for hours and I could have sex. but it's been over 2 weeks now and I'm getting annoyed. idk if it's from my brith control or what. any one else experience anything similar?