Question
I'm going to try to describe this as clearly as possible; when I rotate my left shoulder and/or arm in a circular motion, I feel a popping that seems to emanate from either my upper spine,lower neck OR where the shoulder and the neck meet. It is painful. It's also difficult to tell exactly where it comes from. It's not an audible pop; I can only feel it.  I have noticed that I tend to lean my head to the left A LOT. I don't know if the pain and popping is usual or unusual. No injuries in the recent past, no physical repetition from my job or hobbies. Any ideas? (History: neck sprain more than 10 years ago, back injury around same time, I am short and notice that I have difficulty because I have to hold my arms higher than comfortable at a regular desk and my feet never touch the floor. I have to use a pillow to sit up closer to the keyboard and a stool to rest my feet on. Normally I can only sit for less than an hour and then feel the need to stand to allow my body to recoup. I also often feel as though my spine is jammed as in compacted, almost like a huge weight has been set on my head and over time it just compacts me down).

Answer
It would seem that sitting at a higher desk has your arms in a perpetual "shrug".  This may be causing strain in the upper back/ lower neck area, and causing some muscle dysfunction.  When you rotate the shoulder, the muscle dysfunction pulls the shoulder out of it's normal movement, and causes the pop that you feel.  I would suggest finding a good chiropractor to address the muscle issues, as well as any misalignment issues, and talk with your place of employment to see if anything can be done to correct the improper desk height.