it’s likely Afib. If it’s beating quickly, then it’s likely SVT.
Medications are typically quite effective at treating heart rhythm disorders. These include beta blockers (atenolol, carvedilol, etc.) and calcium channel blockers.
It’s possible for an SVT to escalate to a ventricular fibrillation, which is life-threatening. So, if you’re experiencing shortness of breath, are passing out, or feeling dizzy, get to a hospital.