Many years ago at this point Dan John had done a little talk at CF DC I think you'd find what point #2 most useful, it does require a partner though.
If you really think it's mid back related look to improve thoracic mobility (a google search throws up a bunch of good sites with good suggestions).
"And for crying out loud. Don't go into the pain cave. I can't stress this enough. Your Totem Animal won't be in there to help you. You'll be on your own. The Pain Cave is for cowards.
Pain is your companion, don't go hide from it."