@lilybell I had a frozen shoulder that happened after a diagnostic injection into the shoulder capsule for an MRI. It was so painful that even breathing hurt my shoulder joint for the small amount of movement from rib cage movement and I had to just put my arm in a sling. Other joints were not affected by this. It was a couple of months before a physical therapist could work on my shoulder with increments of forcing the movement to regain proper range of motion and that was painful.

I think you need imaging to determine the problem. A frozen shoulder could mean all or part of the joint or joint capsule is affected. Your physical therapist should be able to tell by feel where the resistance is in your range of motion. If there is a torn rotator cuff, you probably would not make good progress with physical therapy.

Shoulder problems can take a few months to heal. I had a SLAP tear in my shoulder once, because from the front seat of my car, I reached into the back seat behind me to yank on something and felt a sharp pain. I wasn't progressing in physical therapy, and it just had to heal first before I could work on range of motion. I was sent for imaging because PT wasn't helping at that point and the tear was discovered. It resolved without surgery.