Thank you for your query at DoctorSpring.com
I understand your concern.
It looks from your details that at present there is swelling at insertion of supraspinatus muscle.It looks that your swelled up muscle is caught between two surface at special movement of shoulder. Such symptoms may also be there in case of recurrent dislocation of shoulder & tear of labrum.I will advice you to get MRI repeated after few days so that any other changes can be visualised after taking present treatment.
Hope this will help you.
With best wishes.
Feel free to discuss further,