Muscle pain in shoulder

Several yrs ago I had an on the job (medical field) "injury" I did some physical therapy for my shoulder muscle but it did not help. Since then, my muscle is always in some form of pain. I use creams to help but there is only so many times I can safely use them. My muscle pretty much balled up right at my shoulder blade.

I do accupuncture. I've had 1 professional massage (which felt so good). But how can I prevent this from reoccurring? Nights like tonight, im in some decent pain that it's keeping me awake.