26 in shape, one ep of svt 2y ago atenolol 25 mg 2 a day, complete cardio check up rec all clear, getting strange sense of breathing during work outs?

See specialist: Get a second opinion, get more imaging. These sysmptoms are not typical for someone young as you. Consider changing atenolol to alternative medications to see if related.

Pulmonologist: If you've had a complete cardiological evaluation and all is normal, perhaps a pulmonary specialist could evaluate you and determine the cause of your exertional symptom.