@dave56pa I agree that the cardiologist should order a Holter monitor to be worn for a week or more. Probably not going to need a whole week judging by the asker's description of what he's going through.

Sometimes a rate control medicine like metoprolol or diltiazem, bisoprolol, etc, put the heart's natural rhythm, when it isn't having the arrhythmia, into what is called 'bradycardia', or a heart rate slower than 60 beats per minute. Most patients needn't worry if their heart rate falls into the low 50's, especially when they're calm, seated, not experiencing any hardship or strong emotions. But if the heart is forced under 50 BPM, say down to 35-40 BPM, and this is because the rate control medication (calcium channel or beta blockers) is actively suppressing the normal speed, then the patient may experience light-headedness, dizziness, shortness of breath, narrowing field of vision, maybe even passing out. So, to our OP, please keep an eye on your heart rate when you are experiencing the symptoms you mentioned. Also, if this persists, you should contact your cardiologist and mention to that person that you don't seem to be doing well at times with the medication.