Hi @angelicaaustrich and welcome to Mayo Clinic Connect.
We have an older discussion about Costochrondritis/ Tietze syndrome that you might like to read:
https://connect.mayoclinic.org/discussion/costachrondritis-tietze-syndrome/
More information : "Tietze syndrome is a rare, inflammatory disorder characterized by chest pain and swelling of the cartilage of one or more of the upper ribs (costochondral junction), specifically where the ribs attach to the breastbone (sternum). Onset of pain may be gradual or sudden and may spread to affect the arms and/or shoulders." --- Tietze Syndrome - National Organization for Rare Disorders: https://rarediseases.org/rare-diseases/tietze-syndrome/

With your chest x-ray and EKG reading normal, did your doctor give reason as to why they felt it was tietze?