When a medical doctor makes a diagnosis as untreatable/.incurable or for unknown causes, it may be true in their framework only and does not necessarily mean it holds true in other frameworks. This is why some modalities are often called "alternative" or "complementary".

It is nowadays a common practice to seek "second opinions", or opinions from other MD's if you are not sure of the first diagnosis. Then why not a third or fourth from alternative practitioners?

One recommendation here would be: please please do not give up your power to somebody else, whether it is a MD you trust or an alternative practitioner or a religious teacher. It is always only you who can make a choice for yourself. Listening to their advice or suggestions is okay, but you need to make the final decision.