i have a dull aching pain in my left shoulder and back of shoulder blade,with radiating numbness down my arm ,into my hand , also it feels like i slept wrong,feels like a crick in my neck with limited range looking left,and i can hear a cracking type noise when i look to the left and back... its been like this for about 2 years ,dosent hurt with activity ,mostly hurts when arm is at rest...what could it be ..please help