Hello,1. Occasional jerks ,palpitation may not be symptoms of cardiac arrest if all reports are normal.
2.anxity ,
thyroid problem , alcohol ,fear, lack of sleep can cause transient palpitation.
3. Usally pain present in central and left part of chest but there is no hard and fast rule . Do yoga, meditation,avoid alcohol, smoking, coffee, tea...have good sleep and develop healthy food habits.Consult cardiologist.