Chantelschnider, you should see a orthopedist or your PCP, especially if it's been going on so long. Muscles can tear and without proper treatment it could worsen.
I have issues with my scapular muscles spasming. It started last year and it's connected to the damage in my cervical-thoracic spine (C7-T2). It's painful when the muscles spasming & lock up my upper back, making it hard to move. I went through PT/OT last year, and looks like it's going to be a repeat this year. Hugs love & prayers your doctor can figure out the cause & it's nothing major! 🙂❤🙏🌼