Shoulder and Neck Pain

I have been experiencing sharp pain in my shoulder for about two weeks now. The pain is very sharp directly where my pectoralis muscle meets my shoulder muscle. The pain also radiates up my neck into my head, across my chest and down my back and arm. That pain is more of a burning sensation and the pain going up my neck feels like I slept on my neck wrong. I have difficulty raising my arm past my shoulder with no weight and cannot lift my arm straight up with any weight at all. Every time I move my neck or arm, pain shoots across my chest and up my neck. This also happens when I breath in or out. Im thinking I pulled something but Im not sure what. Any ideas on what happened or what to do about it?