???confused

I've had the skyla iud for a month now and my periods have been longer. My period ended about a week ago and it lasted for 2 weeks but since then I've had dark brown or light brown or sometimes red spotting this week along with cramps and tender breasts. My breasts don't hurt as much anymore. Is this normal? Should it look like this or is something up? Glow says I should be getting my period in 9 days but I have a feeling I'll skip it. Should I take a pregnancy test?