Nipple Irritation

I am 20 years old. For the past 3 months or so my nipples have always been so itchy and irritated. I’ve recently noticed my nipples are now always really hard even when i’m hot which is not normal as they’re normally soft unless i’m cold. They’re so hard that when i push them in they stay inverted. Is this something to be worried about or is it just because of dry weather, etc? I start my period in about a week. I tried to look it up and it says pregnancy but i have an IUD and haven’t had sex in a while.