Thank you all for your well wishes. *hugs*

I heard back from the doctor, and both the EKG and the chest XRAY were perfectly normal. The chest tightness and shortness of breath have mostly diminished, and the doctor said if I continue to have those symptoms after about a week, I should follow up with my GP. She said it is almost certainly a reaction to the anesthesia, but it could be something called costochondritis (which is basically chest wall inflammation that has no known cause and goes away on its own without treatment). When I get anxious or upset, the symptoms do get worse, so that's extra incentive to keep calm. LOL