Itching & burning, and soreness at vaginal opening with chunky yellow discharge in days after unprotected sex. surrounding labia red and irritated. ?

You need to be: checked for an infection, possibly BV (bacterial vaginosis). BV is not particularly dangerous but suggests a significant disruption in the normal bacterial flora.The most important thing is to make sure you haven't acquired a more harmful sexually transmitted infection. See a doctor as tests need to be performed/condition treated, either with oral and/or topical meds. Always use condoms!