What is heart attack arm pain like and where exactly does it hurt?

Classic. Usual sub-sternal crushing severe durable sustained, anxiety producing, with clammy skin, pallor and radiation to left upper arm with a squeeze. Much variability!
Left arm. Pain or left neck or shoulder pain that occurs with any other symptom such as nausea, sweating, lightheadedness, chest pain or shortness of breath can be related to a heart attack. You should immediately get evaluation.