@lindalk you should definitely consider getting your lactic acid levels checked.
Symptoms of lactic acidosis include dizziness, extreme fatigue, shortness of breath, and more.

I have the same symptoms you have and all my cardiovascular stuff came back normal. It's only on the off-chance that my husband found all this new research about longcovid patients having elevated lactic acid.

If you have elevated lactic acid, you can go on the PRAL diet for kidney patients and drink alkaline water that is specifically paired with carbonate (not the sodium hydroxide, that doesn't have the right molecule you need. Brand name Body Armor has the right molecule).

Please please get this checked. It can be treated, but if it's not it self-perpetuates!