It appears as though you have an active scar developing. We would recommend a follow up with your surgeon, application of a polysiloxane scar gel such as Plato's Scar Serum; and scar protocol treatment.
Raffy Karamanoukian MD FACS
Without a photo there isn't any way we can help you. The chest is a very common place for people to get a thickened and enlarged scar called a "keloid" and that sounds like what your doctor is trying to treat with steroid injections. I would consult a dermatologic surgeon with laser experience, I have found the best treatments for keloids are with a combination of lasers. I wish you the best of luck, Dr. Emer.