I get this too when I drink alcohol, sometimes are worse than others. It is the muscle between the left shoulder blade and spine. It gets tight, hot and restricts movement, when I deep breathe in I can feel the tightness. It often causes me to have a migraine, and is worse if I am stressed tired or emotional.
I also get this pain without alcohol, when I am stressed tired and emotional. I have been having Amatsu therapy (Japanese therapy) which has taught me a lot about the body and this may be relevant to you.
My liver is struggling, which is also effecting the gall bladder. My liver could be under stress due to a car crash where I got server case of whiplash, (basically the liver hits the ribcage at high impact and then is weakened).
The liver is then pulling on other muscles which are often up the back etc. when you drink alcohol and high sugary drinks the liver then has to work hard which causes it to tighten and then pulling on other muscles on the upper back causing a cramp
My cramp doesn�t go unfortunately as there must be other problems there.
Monitor your pain and see if it is at its worse when you are tired or under stress, I�d be interested to know.
Also try drinking a hot cider vinegar before you drink alcohol, 2 lid fulls to hot water called with cold water. This wakes up the liver and gets it working.
Try Amatsu its amazing.