Do i have an STD?

so my boyfriend and i have been together for 6 months. i was a virgin before i met him and he had one sexual partner before he was with me. when they did it they were both virgins and neither of them had engaged in sex with anyone other than each other. i keep getting thursh and yeast infections which my doctor thinks may be pill related. she also asked if it could be an STD but i said no because there’s no way he could have one. he’s never cheated on me and ik i don’t have one BUT is there any way i could contract one because he had a sexual partner before me? even though they were both virgins?