Why could pulse be lower then 60?

If someone been drinking on a regular base for 10 years. Meaning 2-3 drinks every day(sometimes more) And been taking medication (Felodipine) for blood pressure which has control blood pressure 128/84 and pulse 70. Then if that someone suddenly stops drinking all together for a month (not one drop of alcohol). Could that be a cause for lower pulse to the point you would feel light headed ... dizzy. Medication has been changed from 10 mg to 5 mg two weeks ago. Blood pressure still good but pulse still 54 to 65 range. ECG normal. Blood work normal. Will be seeing a specialist as in the works of appointment. Any ideas why low pulse is happening? This person (male) doesn't exercise and is 30 pounds over weight and hasn't smoked for over 8 years.