It may take several months for a frozen shoulder to heal, but if the discomfort persists despite physical therapy, the shoulder may require additional testing. Inflammation, diabetes, arthritis, rotator cuff issues, and frozen shoulder can all cause pain and stiffness. Although it is not recommended to totally rest the shoulder, a doctor's prescribed pain medications, warm compresses, and modest exercise may be helpful. It is best to see an orthopaedic physician because the pain is getting worse after three months. They might recommend an MRI, X-ray, stronger medications, an injection, or an alternative course of treatment.