What Causes Vaginal Pain During Urination After Having Protected Sex?

dear madam, its chethan from b'lore..doing ma final year BE degree.

i had safe sex with ma partner ... then also she worried about pregency, she getting a pain in her vegina after going to urine... so im geeting fear, v had a sex on 28th of this month, her periods was on 19th ... its a safer period ?? please reply me .............. please begging with u pls.........