Thanks for query,
Your left shoulder pain
with chest pain is due to muscular twitching you gets during electric shock
pain is usually retrosternal. Due to electric shock there are no chances of heart attack but you may get heart stand still leads to rythmic abnormality if it is too strong.The vascular or heart complication is immediate & as you have passed already 2 days now there is no fear of its complication.
Take mild muscle relaxant
with anti inflammatory medicine.