"Lack of diagnosis of my health problem"

I have been unwell for thirteen years: it started with three episodes of terrifying thirst (since then I have completely lost my sense of thirst, which I've been told is impossible). These produced a myriad of symptoms for which no one has, so far, been able to produce a diagnosis, although an endocrinologist has suggested that I might have a damaged hypothalamus, for which he offered no help. However, my GP is of the opinion that I am suffering from Health Anxiety because three psychiatrists say I am, simply because I have had no other diagnosis — Catch 22 situation, it seems to me! Because of this 'diagnosis' my GP has said that he is no longer willing to discuss my problem with me. So I'm left in limbo, steadily getting worse with no hope of getting any help.