Can doctor tell if you are sexually active

Soo June the 3 I lost my virginity to my bf we have been dating for 9 months going on 10 but I got a uti in I told my dad I have an uti an he gave me cranberry juice in water in these cranberry pills to so I been takin them in he told me if tomorrow It still hurt when I pee he will take me to the doctor in he told me what they will do in ask if I’m sexually active but I don’t wanna tell my dad I lost my virginity yet in I was wondering can a doctor tell if your sexually active? Someone please help me I really need it