Hello, When I Exercise I Sometime Experience Sharp Bursts Of

Hello, when I exercise I sometime experience sharp bursts of pain on the left side of my chest, almost near my underarm. I've seen a cardiologist about this issue. I passed my EKG, stress test, heart ultrasound, along with a heart CT. No abnormalties were found, however my pain has persisted and even gotten worse. Unable to exercise I've begun gaining weight back and am concerned the problem with further worsen.