left shoulder pain kinda pushing pain while laying down no
Less likely a heart attack...
You describe of left shoulder pain without nausea, sweating or breathing difficulty. I assume this is the first time you have had this complaint. Let me know if this not the case.
I would also like to know if you are able to climb flight of stairs and perform your usual daily activities this morning without pain / difficulties
Based on the description I don't feel it is due to a heart attack. If you were normal this morning; climb flight of stairs without pain it is an indicator that your heart is healthy. However I will recommend visiting your doctor for clinical examination and EKG. It will allay any fears about heart attack.
Hope this helps. Let me know if you need clarifications.