I'm sorry I have offended you. I'm sure there are many people who have had awful experiences with doctors dismissing their problems and calling it imagination and whatnot. Maybe you or someone close to you has suffered due to a situation like that, and that is awful and shouldn't happen.

The point I was trying to make was that there is also such a thing as health anxiety, and no amount of clear diagnostic tests can cure it, the only way out is to identify the anxiety and treat that. I'm not disagreeing with OP, I'm just adding this sidenote.

Also in some cases you may be dealing with health anxiety, where stress and fear causes physical symptoms that can be debilitating but not dangerous. The fear of having a serious disease perpetuates the stress cycle. If you are in a situation where several doctors give you the all clear, it is very likely that anxiety is causing the symptoms. Ideally the doctor should be able to help with that but you can also seek out a mental health professional.

This article was well worth the read.

Loop it twice around to make the bow, instead of once. My shoelaces have never untied themselves since I learned that

Accepting and allowing all feelings/thoughts/circumstances while acting as you would live your normal life if not anxious. (Dr Claire Weekes explained it best, google her)