My Cardiologist Told Me My Heart Palpitations Are Extra Beats

My cardiologist told me my heart palpitations are extra beats but I am having moments where I feel that I am ready to pass out and my Garmin watch has picked up that my pulse has gone down as low as 45. He tried me on Beta Blocks but they dropped my pulse as far as 32 and I quit taking it.
I am 58 male. Never had health problems, none smoker, 175 pounds. I have no sex drive, but might be because of this stress. My magnesium came back fine. Started taking 250mg with no change. Tried more magnesium but only got diarrhea.
Chest pains most of the day with heart skipping.
I was off my reflux medication for several months but started back three days ago with no change with heart. Vagus nerve?
I scheduled an appointment this Tuesday with my acid reflux Doctor.
I also have scheduled a halter monitor and to see the cardiologist for the electrical side of the heart.
Any thoughts? I need help, my life is very depressing now.