Worried

Okay, so I was suppose to start my period April 5th. I've been having minor, to mild cramps since Friday, April 3rd. I have not started bleeding, just cramping. Last night, I have noticed my nipples have been becoming slightly sore when are touched or pushed up against anything. 
I'm kind of worried as to what is going on, because it's only like this 2 or so weeks before my period is due... Any help?