Ovulated may 16th in late afternoon, had sex may 17th around 3am and 3pm. i'm having creamy white discharge as of may 20th. what could this be?

Vaginal discharge: Most likely unrelated to intercourse. It could be just normal discharge or maybe a yeast infection (although discharge tend to be white and clumpy). If you have no itching,irritation or foul odor I would not be concerned at this time. Take care!

Semen or yeast: If you were trying to get pregnant which I assume you are from your description, then I also assume you did not douche after sexual relations. Now it is coming out. A yeast infection will also give a similar discharge. I hope you get the results you are looking for. Good health.