What can cause recurring bouts of costochondritis thru life? This pain came back suddenly yesterday, does so every year or so. Sternum very tender.

Suspect fibromyalgia. I suspect that this is fibromyalgia. Fibromyalgia causes widespread Musculoskeletal pain and pain along the chest wall and the sternum even cause costochondritis. It is also known as tietz-tietztsyndrome can occur in the setting. You need to have your physician evaluate you and have you see a rheumatologist.