I understand your feeling of violation. He should have asked you if it was okay even with your mother there. It's good bedside manners to communicate (especially with pre-teens since most adolescents are generally uncomfortable with their bodies to begin with without someone touching it) about what they're doing to your body. Sometimes doctors get in hurries and don't think about their patient's feelings like they should but it doesn't mean it's right.

What does your T say about it?