"Wasn't listened too and treated badly"

I was refereed by my GP to see a cardiologist because I had been experiencing palpitations, chest pain, abnormal heart rhythms and some kind of twitching in my attires mainly in my neck. I am only 21 years old and have been having these problems for about a year now and have had numerous tests which have all come back normal such as ECG's, Holter Monitors etc however my symptoms have continued to worsen and I now fear death or at least a very horrible life. My experience at the hospital was all good until I went in to see the cardiologist. They wouldn't let me finish sentences and simply didn't listen to what I had to say or take me seriously. I was trying to explain my symptoms and the doctor wouldn't allow me to do so, simply stating that all I should be talking about is palpitations and chest pain. I feel its unreasonable that I wasn't allowed to explain my symptoms such as the suspected twitches in my arteries that I get which I have no idea what they are and variety of other things such as tingling throughout my body, irregular heart beats etc. The doctor suggested I should get a Holter Monitor but I have already had one of these and it detected nothing so I feel it would be a waste of time. Overall the doctor did not seem like a very nice person and didn't to appear to really care about their patients at all, I assume the doctor treated me like dirt because of my age. Just lacked any form of professionalism, I wanted to suggest that I have a cardiac stress test and a potential ultrasound of my Carotid Arteries. I understand it's very rare for someone of my age to have this type of problem but it isn't impossible and the doctor was acting like it was.