What Does A Bump On Top Of Ear Suggestive Of?

I have an unexplained bump about 5cc (I think) from the top of the ear. My neck is always in pain. Had an ultra sound done with no real results. Chiropractor stretched the neck. I usually have chronic neck pain due to my job but this is different. It will go away with advil or muscle creams. Since I had breast Cancer, the general doc wants a CAT scan and sent the ultrasound results to my oncologist. What is the thought here? Thanks