tachcardia and palpitations

I was having chest pain and I went to the er was told that I had palpitations and tachycardia. I was also advised that I had some right or left atrial abnormalities. I did not have any heart issues until last year Nov when I was hospitalized with food borne illness and I was told then that it was a one time thing and that the antibiotics that I was given would work for my heart too. Well, a year later I have had more chest pain, and sob and pain radiating from my jaw all the way down the left side of my arm to the point that it tingles and hurts at the same time. I had a stress test and 2 min into the walk my bp rose to 187/99 then at 5 minutes it was 212/116 and I was not even walking that fast. The cardiologist tk me off the treadmill and I had sob and chest discomfort. He put me on Tiazac 180 and I still have a racing heart sometimes. I was not told exactly what was wrong with me but on my paper from the doctor for the diagnosis he had C.P.,tricuspid valve disorder and tachycardia and palpitations. I am 28 yo and was 27 when this happened. I go to the Er every time I get chest pain and then they treat me like I'm overreacting. The last time the nurse commented to the tech that it wasn't like I was having a heart attack or something, then when my husband told her that we heard her and then she did the EKG, she apologized caused it showed sinus tachycardia and right atrial abnormality and borderline T abnormalities. I was upset that she also accused me of using drugs and I don't even use drugs, never have. I also wanted to know if my lungs being smaller than normal can contribute to these problems that I am having. my M.E.P. was 21 and my M.I.P. is 48 also my TLC is 69. Not sure what that means, but the pulmonologist that I see said that my lungs are smaller than they should be with my age.Should I be concern that I am having a heart attack. I also get an electrical pain that hurts when I inhale on my left side under my collar bone when I feel like something is squeezing my heart.