So, I would suggest perhaps going to a sports injury doc, they deal with things like rotator cuff injuries all the time, and he can evaluate you and perhaps order physical therapy. On your own, you could instead visit a professional
massage therapist, deep
Swedish massage a few times might break up the pain in there and relieve your headaches.
Now, anytime a person is in a lot of pain, they will have your other symptoms of being tired, not able to focus, and emotional problems.