500mg Naproxen and Spotting

Does anyone else take 500mg naproxen for their period cramps? I just started my first dose and my period was supposed to start today and I started spotting a few days ago very light watery red blood and now it's dark brown/red and it's not even enough to have to wear a pad. Had this happened to anyone else? My doctor said it would lighten my flow but I pretty much don't have a period right now.