Upper Back Injury, Form Issue?

 I few months ago I woke up with a slight annoying pain in my left upper back. It didnt' bother me much and I didnt pay much attention to it. As the time went on I realized that it wasnt going away and when I turn to the left or right it kinda feels tight. 

When I didnt deadlift for a week it got a little better but when I did deads again it started being really uncomfortable again so I think its from deadlifting - no deadlifting for a while.(that same day I did pullups and dips weighted so I dont think it could be from my other exercises)

 My question is this my form or maybe an imbalance? since its only on one side. I ve been doing deadlifts for a about a year and   have been told that my form is generally good. 

Also I cant get to the pain by pressing on it or when others press on it I dont feel anything. Its strictly from turning left or right or when I slouch and lean forward. I dont get any pain during deadlifting either. But when I put the bar down and turn slightly I definitly feel a lot of stiffness. Any help is appreciated.

if it’s under one of your shoulder blades it could be a scapular thing…

is it along the spine? I torqued my upper left middle back and it seems to be the lateral stablizers. I feel it when rowing with the right arm only or slouching, as you mention. Doesn’t keep me from training, just annoying, like some guy tapping me on the shoulder over and over and saying “Hey, Mister…hey, mister…”

high rep unweighted side bends seem to make it feel better for a time. Haven’t tried self-ARTing it yet with a foam roller, that may help…