Hi barbie, You could have BV (bacterial vaginosis) get to your doctor, him or her should be able to sort you out with the right meds, but this has a habit of coming back.
Good Luck
The white discharge after sex is normal the discharge is body's own way of lubrication during sex. The discharge also increases during the time of ovulation. It is nothing to worry about just keep track of your periods and if they are late then 7 to 9 days go for a home pregnancy test. If you notice thick curd like vaginal fluid then it can be yeast infection. Please consult a doctor in that case.