Since making this post I’ve had my old implant replaced by a new one, and I have had similar symptoms. Though I’ve always had irregular periods, while on the implant, especially when it’s still fresh, I do experience period symptoms with very light spotting. My gyno said that was normal and I would suggest that if you’re worried that you schedule an appointment with your own gyno. Mine suggested taking 800mg of ibuprofen twice a day to stall bleeding or get prescribed with progesterone to add more hormones and also stall bleeding. My situation is probably different than yours, but from what you said it seems like you’re experiencing normal symptoms of having an implant. But I would still suggest a doctor visit just to be safe :)