When i lay down on my back , my chest hurts, superiorly approximately on the apex of the left lung , knowing that i smoke , should i check?

Probably not: Chest pain that occurs only in certain positions is generally not related to a disorder of the heart or lungs. It is typically a musculoskeletal pain that resolves with time and\or mild painkillers like Tylenol (acetaminophen) or Alleve. It is imperative that you stop smoking. There is no reason to damage your heart and lungs while increasing your risk of bladder and other cancers. Stop while you can.