Mine wasn't from Costochondritis, it was from severe muscle spasms in my neck/shoulders/upper back that also involved the inter-coastal rib muscles. It was very different from the Costochondritis I had during pregnancy #2 , that time it hurt right in the breast bone area and it was tender to pressure there also. Really painful when baby kicked or pushed on the area internally.

[Costochondritis is inflammation of the junctions where the upper ribs join with the cartilage that holds them to the breastbone or sternum. The condition causes localized chest wall pain and tenderness that can be reproduced by pushing on the involved cartilage in the front of the rib cage. ]
http://www.emedicinehealth.com/costo...article_em.htm

The spasms affected my whole rib cage, I still have some lingering tender spots in the inter-coastal muscles. Those could be unrelated to the spasms so long ago though.