Could I be pregnant???

I’ve had the iud skyla for a year now and get my period every month. Recently i’ve been really fatigue, nauseous and had cramping. Which the cramping didn’t really worry me bcs I always cramp a couple days before I start my period. I was spotting last night and thought finally my period is here but today I just have brown discharge and also i’ve been having sore boobs and was a little dizzy. Could I be pregnant? Or are they just iud side effects. Which I never get and this would be the first time I get all at once. I took a pregnancy test yesterday and it was negative.