Hi welcome to Health care magic forum. topral xl (metaprolal) has specific side effect of sudden decreasing of the dose , in that case there can be side effects like chest pain
, breath less ness etc. your feelings could be due to such side effects only.
You would have reduced the dose to be less than half, so such symptoms has happened. If you want to stop the drug you should do it with the supervision of your doctor.
You have no cardiac problems, but you have hypertension
for that only your doctor might have prescribed the medicines.
Wishing for a good health , and thanks for calling.