Chest pain center left side. Reports.

Hi. After recovering from covid palpitations started after 10days. For that advised to continue concor 2.5mg for 2 months tapering dose. Currently taking 1.25mg. Sometimes i feel pain on my center left side of the chest. It is very occasional. Sometimes happens during sleeping, standing or walking. I have consulted cardiologist had done multiple ecg all came negative. Recently done tmt test that also came negative. Cardiologist told may be due to gastric issue so gave me medicine for one month which i continued still pain is there. It comes randomly then goes away. Mostly it is center left side sometimes complete left little towards upper area. I am completely in vein what is this pain. Is it heart related or anything else and everyday going in fear if something will happen. I have attached my test reports.