What Causes Pain In The Neck And Shoulder Blade Area?

hello, i have a burning, itching, tenderness to touch sensation flowing through my left arm from the should blade towards my wrist. Its been present for a week. I thought i d gotten into some due to the itching, which caused me to scratch until i almost saw blood; when in fact there s absolutely nothing present. so i ve been very attentive and i have noticed that about 5 days i had neck pain. If i moved my neck slightly a shard bolt would be present. if i applied pressure in the area of the back shoulder blade, top of shoulder, and side of neck it would fade. if move the shoulder in a perfect position it completely goes away but only for a split second because its an abnormal movement. The neck is 90% better but my are will not allow me to sleep. I noticed today i m carry as if in a sling, applying very hard pressure to my bicep cuts the pain off from that point and below, but that hurts like a dull pinch.