I had an IUD placed 01/12/2018 so I'm just over a year of having it in. I haven't had periods really and when I do they're super light pink spotting and last not even a day. I got a normal period with cramps and regular bleeding like 8 days ago, and it hasn't stopped, I have no other discomfort, and it doesn't show signs of stopping. My strings are in place and I took a pregnancy test and it came up negative. What is going on?????