I have 3 herneated discs in the thoracic spine. The result is excruciating pain just to the left of my sternum. Esi has not worked. What's next?

MRI/CT myelogram. Herniated discs in the thoracic spine is unusual, outside trauma, you need further investigations and orthopedic or neurosurgical advice.
A better diagnosis. It is unlikely that your herniated discs have anything to do with your sternal pain. They are most likely an incidental finding.