Nexplanon implant !

So I got my nexplanon 2 days after I ended my last period . I had my daughter 7 months ago , and I'm not looking to have another one any time soon ! But my period is due tomorrow and yesterday I had some brownish pink discharge, still no period . And today I had some pink discharge but still no actual bleeding . I've been nauseas today eating pizza and the smell of my boyfriends cologne . I took a test and it was a negative but could it be a false negative ? How early is too early and if it isn't , is it just the side effects of the nexplanon ?!