Nipples bruised

Ok, so I’m scheduled to start my period in about 4 days. But I’m curious... my nipples have been extremely sore to where even the touch of my shirt makes them hurt and they also look a little bruised. (Just the nipple itself) I’ve also been more tired than normal. Just wondering if that could be part of starting period soon or if it could be more. Of course I want to wait on testing until I know for sure if I’ve missed any days of starting.. has anyone else had this before?