I got thick, white, stringy discharge on the day i was supposed to have my period. i'm 2 days late. this has never happened b4. what could this be?

Likely normal: There is some degree of variation in when periods start and how long they last that is normal. So having the period be 2 days late may not mean a problem. If you are sexually active make sure you're using birth control so pregnancy isn't a concern. Stress commonly causes periods to be irregular. And sometimes hormones are off. Vaginal d/c with itching, irritation or odor can mean a vaginal issue.