I have had a sharp, burning pain right above and to the left of my right scapula. I noticed yesterday at the gym while doing overhead presses that it had become quite a bit weaker that the other arm. I don't recall any injury and I first noticed it in the morning about a week ago. The interesting thing that I have noticed is that it is not there when i wake up. But, after about 15 minutes it starts to come on. I am working on my posture, mouse, and monitor position at work to alleviate looking down and reaching. Could this be the problem?