Hello and interesting question, hopefully I'll be able to help you out a bit. First of all, it would be very, very unusual to have any kind of hernia in this area, so I wouldn't worry about that at all. There are a couple of possibilities that I think it may be.
First of all, if the small bump is along one of the edges of the sternum, it could be what we would call a tender or "trigger point". These are very common in this area because this is where the pectoralis muscles attach, as well as where the ribs interact with the sternum. So this could be a possibility. These areas can also become inflamed when your back is irritated because the back end of the rib interacts with the spinal vertebrae, so if one end is out, it's likely the other could be as well. Either way, inflammation at the joint between the ribs and sternum is quite common and is called costochondritis. It's typically treated with nonsteroidal anti-inflammatory medications or ointments.
Secondly it could a small cyst, but that would be quite unusual, and probably not cause a great deal of issues.
I hope this helps, and it may be worth taking some nonsteroidal anti inflammatories such as motrin or ibuprofen, or if you have insurance there is also a new prescription gel called voltaren gel that works well.
I hope this helps, if not, let me know, best of luck...
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