My heart rate keeps dropping from 50-60 to 39/38 I get tired easily & cannot exercise as much. I feel dizzy & it feels like blood rushing in my head?

Call Emergency. This heart rate is too low, and if it is causing you symptoms, then it is an urgent situation. I suggest you call for emergency medical assistance.
Bradycardia. You migh suffer from a condition called Bradycardia, there are different kind of Bradycardia, if heart rate stays low and especially doesn't go up during activity the cardiac (heart) out put drops and therefore the blood pressure drops and the blod flow to the brain decreases and causes dizziness, you should see a doctor for an ECG and referral to heart doctor for possible event monitoring.
See your doctor. While it's rather uncommon for slow heart rates(bradycardia) to creat significant problems, it's not impossible. If your blood pressure is already low/bordeline, combine that with a slow heart rate and things can get worse. You could even pass out. Please seek help in person. Best of luck. .

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I am experiencing irregular heartbeat, dizziness (better by: rest) (worsened by: changing head position, after exercise, sitting upright), vomiting and heartburn (gerd). The following also describe me: Nausea, Lightheadedness, Fatigue, Rapid heart rate,

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