X-ray for neck pain came back clear except for small spot on breast bone. doctor says don't worry about it but i am.

What do you mean by: What do you mean by spot. I assume you are speaking about a density in the sternum (breast bone) Usually this represents a benign bone island unless the patient has a known history of malignancy in which case metastatic disease must be excluded. Depending on the size of the density, bone scanning may be helpful. Sounds like your doctor thinks it's a bone island