Can Pain In Arm Be Due To Muscle Tear While Doing Cardio?

Hi, I'm a 17 year old male and have recently started working out again and doing cardio after 6 months of "laziness". 4 days ago I started feeling pain in my left arm and heart which still persists up until now. The pain in my arm is even greater in the morning when I sit down in the bus on my way to school. Could it be that I've teared a muscle in my left arm by working out too much, or is it something else?