but that's not on YOU. if someone cries wolf and then some day happens to get sick it's on them for doing that. this is why you call him out on his stories and ask for evidence of any of it. matter of factly ask if you can see the dx or progrnosis or whatever they call it. ask him if he can tell you how much the exams would be (not that you can help but someone that says that they can't afford it must know the price) YOu can find out a lot by testing the information to seek consistency. When you find inconsistency in their story you probe further.

If you do all of this with an air of curiosity and concern, someone that is truthful will not take offense.