Based on your history of a recent fall, pain with reaching your arm behind your back (internal rotation) and restricted shoulder movement could be due to a rotator cuff injury (especially subscapularis), shoulder sprain, labral injury, or less commonly an undisplaced fracture. A clinical examination is essential to identify the exact cause.
Next Steps
I recommend consulting an Orthopaedic Shoulder Specialist as soon as possible. An X-ray of the shoulder should be obtained initially to rule out any fracture or dislocation. If the X-ray is normal but pain and restricted movement persist, an MRI may be required to evaluate the rotator cuff, labrum, and other soft tissue structures. Treatment depends on the diagnosis and may include medications, a short period of sling support, physiotherapy, or surgery in selected cases.
If you would like a detailed assessment, you may book an online consultation with me through Practo. I can review your symptoms, examine your shoulder movements virtually, and guide you regarding the appropriate investigations and treatment plan.
Health Tips
Until you are evaluated, avoid lifting weights or repeatedly forcing your shoulder behind your back, as this may worsen the injury. If you are unable to lift your arm at all, notice a visible shoulder deformity, develop numbness in the arm, or experience severe pain, seek immediate medical attention.