I'd second the suggestion to try chiropractic sooner, not later. The longer you have something out of place, the more likely you will end up with permanent damage, which would put a crimp in your hiking and packpacking for the rest of your LIFE. Pain between the shoulderblades could involve neck muscles, shoulder muscles, or both. You really don't want to fool arould with the vertebra involving what could develop into dowagers hump.

Not trying to scare you, but do take it seriously.

Been there, done that.