yeast infection

I went to my appointment for my prenatal appointment and everything was fine, but she was checking me for the group b test I think it's called and it hurt for putting it in my vagina. She said it was very tender than it should be I haven't had sex since November could that he the reason why it was tender? But she said I could have an infection, but just wanted to see if I do or do so she took another swab. I don't have any signs of it or anything??