The best advice I can give is actually to go for a check. There are reliable tests to check for infections such as chlamydia, gonorrhea, and other possible STIs. While a white discharge is often associated with a fungal/ yeast infection, which sometimes flare up with the menses, there can be a concurrent bacterial infection which may or may not be sexually transmitted.
Some of these STIs in women can be silent, yet can have important sequelae. For example, STIs like chlamydia and gonorrhea are associated with pelvic infections that can lead to subsequent damage to the fallopian tubes (which bring the egg from ovary to the uterus), and this can result in infertility or an increased risk for future ectopic pregnancies.
Anyone can be at risk for STIs as long as there is unprotected intercourse, that is, sex without the use of condoms. Of course, we would like to emphasise that prevention is better than cure, so insisting on use of condoms from beginning to the end of sex would be a good way to protect yourself.
Hope this helps.
Dr Fong Yoke Fai