sadgirl – everyone is telling you to stand up to your parents, rav etc without having a clue what kind of relationship you have with them. Would your parents be concerned about yichud? If yes, then if you don’t feel able to tell them you are quitting or scared etc, you can tell them you are concerned about being there so often alone. They themselves may say it is a halachik issue and tell you to leave.
You do have to understand, however, that without more info the story does sound a bit off. Dr’s don’t typically leave the office when patients are there, it would be irresponsible and unprofessional. And I don’t remember you saying it was a basement like one poster suggested, is it out in public?