Hi, how's it going?
I had my medical exam today since I'll be at a spa from the fourth of September.
One thing to note is that a 'sanatorium' may be a spa, as in a resort, or a sanatorium, as in a place to recuperate from an illness. In Polish, 'sanatorium' is used to mean both depending on the context. In the US, sanatoriums for recovering from an illness don't really exist today, but they do in other parts of the world including Poland. Also, 'badaniach', is a generic word for a medical exam, but can be used to describe all sorts of medical tests. You can't derive anything specific from her message about the nature of the exam.