Sudden period after 4 months of having Nexplanon implant..

I have not had a period since I got my implant which was Nov. 27th of 2017. I had some spotting the first week I got it. And then I spotted for about a month during my break up. Which was just stress. But this is definitely a period, I just started a few hours ago. I am worried Bc I have just became sexually active with someone new. (I haven’t made an appointment to get tested and stuff yet. I planned on doing that at the end of this month.) Could this mean that my implant is no longer affective? Or do you think my body is just finally used to it? I dunno it’s strange Bc rn I’ve got a bit of stress going on whereas I didn’t when I first got it.