It is not advised to start long-term medication without a proper diagnosis, as bilateral shoulder and arm pain lasting three months requires clinical evaluation. This could stem from cervical spine nerve compression, rotator cuff issues, or systemic inflammatory conditions. For temporary relief, you can take over-the-counter pain relievers like Acetaminophen or Ibuprofen, if safe for you. However, you must see a physician or orthopedist for a physical exam and potentially imaging. They can prescribe targeted treatments, such as physical therapy, prescription anti-inflammatories, or muscle relaxants, based on the exact cause.