Upper back pain

I have hurt myself lifting at work. It started as a moderate sting centered on my spine between my shoulder blades, shortly below my neck. I kept pushing myself, thinking it work just work out, but it got much worse over the next hour or so. Now i can't lift more than a pound or two without excruciating pain. The only position i can get comfortable in, is lying flat on my back. Even sitting or standing is painful. An odd thing about it is that sometimes when it hurts the most, the pain spreads right up over my shoulders and into my upper arms. Only the backside of my arms hurt, it's not a stinging pain like in my back, but more of a hot, weakened feeling. It's been 2.5 days since the injury and when i awaken in the morning, it feels about 30% better, within an hour or two of moving around, it's back to the way it was.