TMI maybe ..

So my period was 22 days late, my SO and I aren't trying to conceive but aren't taking all the precautions either. I'm usually regular, off by a couple days maybe. Finally today AF shows up, but it's really painful. I've never had cramping before, as weird as that may sound, and for day one it's quite heavy. I've been really nauseous, tired and sore boobs which could all be AF symptoms. 
I've googled it but that's never a good idea because I'm "dying" and now have "cancer" according to google. 
Just wondering if anyone has experienced this or may possibly know what's happening?