Tingling in hands, feet,and face, SOB, lightheaded

I was a competitve bodybuilder for 5 years and trained daily up until recently when I felt like I was short of breath, tingling in my hands and feet, and lightheaded after my workouts. I then began experiencing tingling around my face and hands so bad that on a few ocassions my hands would actually curl and  I felt like I was going to faint. This lead me to all out panic attacks like symtoms (symptoms) after my workout and now during just light exercise and on occassion while driving.  Even during light exercise (10 min elliptical, 50 - 100 pushups), Ill get tingling and lightheaded, I always have too burp alot. My heart rate at night can drop as low as 43 bpm and I know when it does because I feel SOB, but my doc insists that this is normal because of my athleticism. This has made me avoid exercise for for the better part of one month and Im now getting agoraphobic due to the fear of having these symptoms, my life is a wreck. I had a job opportunity that paid extremely well but required I fly out for my training and drive a mere two hours from home once a month, both of which I just cant do right now. I even gave up the opportunity for a speaking part in a major film ( I have done films in the past), because I couldnt fly to California. I am AGAIN going through testing with my physcian to rule out any physiological issues that might be going on, but so far all blood work and heart exams (ekg, echo) have returned normal. They noted a wenkebach arrythnia but were adamant that this cannot cause my symptoms, it is a benign condition.  I am scheduled for my final exam next week (holter x 3days) and if this comes back unremarkable then I am assured that I need to get an anxiety issue under contro, but I cant help but to wonder if it is still cardiological or even pulmonary. I go to one of the best hospitals, MGH in Boston MA, but I cant seem to get any answers other than to take anxiety meds. I will do that if they would rule out other possible answers. It is just hard to believe that my exercise tolerance one day was great allowing me to perform moderate to intense cardiovascular exercise for 40min to 1hour and weight training for an additional 35 to 50 min with heart rates upward of 160 beats per minute and than a week later I can barely tolerate 15 - min of exercise and heart rates of 125bpm. My heart rate returns to 70 - 90 bpm within a minute or two but remains there for about an hour after exercise even though my resting heart rate is around 50 - 55 bpm and can drop in the 40's near bedtime.  Please I need additional input on this because Im unsure whether or not to seek the help of another physician.