I've i've had thick white milky discharge n some clear discharge. my boobs are sore n i have slight cramping n today i was suppose to start my period?

Check for pregnancy: If you have sore breasts and are late on your period, you should start by making sure you are not pregnant! if your home pregnancy test is negative then your symptoms aren't coming from a pregnancy. Your gynecologist can evaluate you for a vaginal infection that might be the cause of a milky discharge.

Pregnant?: First decide if it is possible that you could be pregnant and do home pregnancy test. Other causes birth control pills menses etc.