I have a question I was suppose to start my period 5days ago I'm having cramping like period cramps…

I have a question I was suppose to start my period 5days ago I'm having cramping like period cramps but I'm not bleeding it goes sometime in my lower back I have taken a test but came back negative do u think it's still to early to test I did have the IUD removed January 25th but I did have my first period bout a month or 2 ago I've never been late on my period is it normal to cramp does that mean the egg is implanting