Had sex with new boyfriend, 10 days later had watery thick white discharge then period now discharge is clear pale pale white or creamy what could be?

Infection? STD?: Any new, unexplained vaginal discharge should be professionally evaluated. The timing suggests an STD like gonorrhea, chlamydia, or trichomonas. Or perhaps bacterial vaginosis, an overgrown of mostly normal vaginal bacteria, but often associated with sexual activity. BV or trich is especially likely if you also have strong vaginal odor, often with a fishy smell. See a doctor soon.