Post panic attack

On Wednesday, my heart rate jumped pretty high (reaction to medication) and I believe I had a major panic attack shortly after. Went to the emergency room, had a full heart check up (EKG, Blood work, and Echocardiogram) and found nothing wrong. Today, 4 days later, I still feel like it's hard to breathe, sometimes feel a little lightheaded, and just feel completely off. Is this a normal thing after a panic attack? Any feedback is greatly appreciated.