Moderate shoulder pain, seeking answers?

I have moderate shoulder pain that originated around the pressure point beneath my left shoulder blade and is now radiating up my neck and down my left arm for two days. My arm had a tingly feeling and feels weak. I have some mobility, but not full range of motion without a tinge. It's mostly in my left side and also hurts sometimes when I walk,move my head, etc. I have had muscle sprains before and this is very different with the shooting pain. I have fractured my sternum about 3 years ago and the pain (albeit less), is familiar. I'm considering seeing my doctor or chiropractor about this issue as it is not getting better nor worse. I wake up extremely stiff and my hand currently is twitchy and shaky. I'm left handed and it's on this side so it's hard for me. I also have trouble sleeping...could this be a muscle tear, strain or something more?