I have sharp chest pain in my leftside?

Chest pain: You need a physician visit to diffrentiate cardiac pain vs. Non-cardiac.

Multiple things: Could be a problem with skin, nerves, muscle, shoulder, lung, heart, or stomach. See your doctor for a more thorough history, physical exam and further evaluation. If you sleep on your stomach you could have a neck strain that radiates pain to the chest or arm. Get checked out just to make sure.