That's strange, but not necessarily surprising, as medical secret is one of the most important rules to follow for doctors, and you are not, say, close family (and even then, they are reluctant at best). Unless he threatens you or himself directly, I don't think anything could be done, from a medical standpoint.
On the other hand, I agree this situation should be taken care of, and that he is lucky to be with you. You could try again, but this time, meeting a psychiatrist instead of a general practician. Since it is his job to diagnose mental illness, maybe he will be more listening (although I actually have no idea what will happen), especially because in disorders like schizophrenia, the person is often unaware of what is happening to them.
I hope this answers you well !