To treat a rhomboid strain with physical therapy, start with gentle stretching exercises like shoulder blade squeezes and chest openers to relieve tension. Strengthen the upper back and shoulder muscles with exercises such as rows and scapular retractions to support healing. Use ice therapy to reduce pain and inflammation in the initial stages. Gradually incorporate range-of-motion exercises to improve flexibility. Maintain proper posture during daily activities to prevent further strain and aid in recovery.