Denial is definitely part of an anxiety disorder. If you're willing to try all these other things why won't you try treating the supposed anxiety too? They aren't saying you are imagining this, mentally ill people are sick. It's just another cause, it doesn't mean you are somehow weak anymore than getting cancer is weakness. Anyways, if they don't have a physical answer and they still want to help you they can either say "I don't know" or they can suggest you seek a psychosomatic explanation. They're not doing this for cruelty, it's just the best option. And a far more likely option, as these doctors see people who imagine their symptoms all the time. Of course you could have some rare thing nobody knows about but hypochondria or a somatoform disorder are much more common. They're not imaginary and they're not anyone's fault, they just come from a different source.
Try an antipsychotic, maybe. This is not an insult, if it works then you are better and if it doesn't then you haven't lost anything and you can rule out one more thing. I've never seen a good doctor speak in absolutes, if your doctor tells you there is no possibility of a physiological problem then either what you are claiming is really, REALLY weird (and thus hard to diagnose, or possibly mental) or your doctor isn't very good. If you are told this multiple times then it's probably the first one.
Think from their point of view how frustrating it must be to see patient after patient complaining of the same symptoms and not be able to find anything wrong with them. And you know anxiety is very commonly the cause for those symptoms, but if you tell them it's probably anxiety they get mad. I'm not saying this is true in your case, but doctors have to lose interest after trying to diagnose dozens of patients and finding only anxiety. I've had a doctor arrogantly tell me that they can pretty much tell when someone is sick just from looking at them. What this meant to me was that if you look healthy then your complaints aren't important to them because you're probably just another mental case. But I can't really blame them for this attitude because so many of us are mental cases. And it's hard to stay interested searching for a needle in a haystack.
Maybe they have heard all that before from others wanting presc<x>riptions for medication or a cronic pain condition. Tell them if it is anxiety, you want to be treated for anxiety.
st johns wort is good for calming down, i take it