Suggest Remedy For Irregular Heartbeat After Taking Oxyelite Pro

Hello, I decided to purchase the Oxyelite pro and started today. I only took one pill today even though it recommends three. The reason I only took one pill is because I usually don't result to medication of any sort unless it's my last resort. Needless to say I am having an irregular heart beat and feels like I'm having a heart attack but i know I'm not. What can I do to decrease this feeling?