My patients and I must have a mutual understanding of WHY we are playing. Our objective is to achieve a play exam as realistic as possible. When I step into my exam room I am in the mindset of a real doctor and that is my sole focus, the same opportunity as a real doctor to put my education and experience to work.
It is imperative that my patients disclose their history accurately. In some cases I may need further education on the medications they take and any conditions they may have. That allows me to prepare myself and also broadens my knowledge in the process, often allowing me to see certain pathologies first hand that I may otherwise only see in textbooks. Every patient I have seen has added to my knowledge base and experience because they provide me a detailed history.
I would have extreme objections to a patient inventing symptoms, but even more so displaying false pain or discomfort. It is agreed in advance that I am going to perform a detailed examination so the patient has no need to fake symptoms "to get me to check further". Likewise, I would never suggest that a patient has any type of problem simply so that we can check further. We know what we are going to check before we start and I am going to do so in the most educated and professional manner possible.
Above all, my patients must agree that I am not qualified to offer any form of medical advice or opinion. On the reverse, I have over 35 years of education and experience behind me. My exams often go places no one has gone before and there is a very real possibility I may discover something unexpected. Although I am not "qualified" to provide any type of diagnosis, neither am I qualified as a firefighter. If I saw your house on fire, I would do everything humanly possible to help you. So my patients must agree that if I do find any reason that they should see a real doctor, they will do so without hesitation after our session.
In the same way as a real doctor, you should be honest and fully disclose anything about your health. You should never create a fake scenario or symptoms, even if it is just for fantasy roleplaying.