Enlarged heart, chest pain and high blood pressure

56 yrs old, 190 lbs, normal echocardiogram except enlarged lt atrium. normal cardiolite stress test. BP during stress test lowered to 130/70, immediately after exercise 190/100 stayed up for 5 minutes. BP was 140/80 just prior to test. Cholesterol is 230. I am dieting and eating very healthily now. But when I try to walk fast or up stairs I get very short of breath and get mild chest pain across my chest, my arms get very tight and heavy and my fingers get numb. My doctor seems unconcerned. I want to become active and healthier but my symptoms when walking are very fightening. What should my next step be? I have not seen a cardiologist, if my doctor is unconcerned, should I just go over her and would I be wasting a cardiologists time? I also get extremely sweaty, like a cold sweat when I am really busy, the sweat pours off me. Not like a hot flash, I am very familiar with those.