Hello I Am 45 Year Old Male Have Had Electrocardiogram,

Hello I am 45 year old male have had electrocardiogram, stress test, electromyogram blood work and urine 2 times each in the last couple of months I take cholesterol medication only everything else is normal and all the exams came back normal but now my pulse rate is lower than 1 year ago before 68-72 but now 50-60 and below with increased periods of dizziness and SOB and chest pain with more visits to md's with no answers still. My stress level varies not obese occasional exercise former military, former marathoner now more weightlifting 2-3 x per week, decent diet. will see me again next week looking for answers.