ladies I need some advice

I had my mirena out in March, I've had a pretty normal cycle or at least have symptoms of gettin af. Last month I had no symptoms at all it was a week early I woke up with extreme cramps which isn't normally how it happens. I've never heard of implantation bleeding before could this be it? Now I have two weeks until the next cycle but I'm bloated again I'm not sure what's goin on