I just notic a bone on the left side of my chest under the connection of the collarbone and manubrium. no pain, and i believe it came after bee stings?

Prominent cartilage?: May be a prominent costochondral cartilage. The beesting was probably coincidental although there may be a small persistent scar over the area from a resolved bite reaction from the sting as another possibility. Or there may be some other abnormality. Best here to be examined by a doctor licensed in your area - this should be able to sort through the possibilities to make a diagnosis. Good luc

Evaluation: You should see your doctor to be evaluated and have CT and blood test to find the cause , so be treated.